They're off! The GOP debate launched the campaign. What's next? An arrest, for starters.

Now that the first GOP presidential debate is over, the five-month sprint to the Iowa caucuses and early primaries is just beginning.

So what's next?

For starters, there will be a big moment for a candidate who wasn't among the eight on stage in Milwaukee − Donald Trump − as he gets set for a command appearance at the Fulton County jail in Atlanta. The coming weeks will bring a winnowing of the large field and a guessing game about whether anyone new will enter the field.

The upcoming milestones will determine which contenders survive into next year; who (if anyone) gets traction to challenge Trump, the current frontrunner; whether the nomination will take months to sort out or will be effectively settled almost as soon as it begins; and where Republicans will stand on issues for the general election, such as abortion, Ukraine and the economy.

Here's what to watch for.

Thursday: Out on bail, again.

In Atlanta late Thursday, Trump was booked, photographed and fingerprinted on criminal charges of trying to overthrow the 2020 election.

Fulton County District Attorney Fani Willis had given Trump and his 18 co-defendants until noon Friday to turn themselves in for arrest and processing on a 41-count racketeering indictment. Trump flew to Atlanta from Newark late Thursday to be processed, then be quickly released on bail. "This is a sad day for America," Trump told reporters before he got back on his plane. "We did nothing wrong."

The extraordinary scene at a notorious county jail eclipsed some of the day-after news coverage of the debate. That limited the boost biotech investor Vivek Ramaswamy might have gotten as the center of attention and the attention former UN ambassador Nikki Haley might have commanded as the contender who first took on Trump, her former boss.

During this campaign, Trump may find himself spending more time with his lawyers than he does with voters. The booking in Georgia will be followed by months of pretrial appearances in New York, Washington and Florida. All that will complicate his schedule, consume his attention, and cost millions of dollars in legal fees. Politically, though, the indictments so far have hardened his support and prompted most of his rivals to defend him.

Consider the respected Iowa Poll, sponsored by The Des Moines Register − part of the USA TODAY network − and NBC News. The survey was in the field when the Georgia indictment was announced. By 6 percentage points, those interviewed after the news broke were more likely to believe Trump's assertion that he was elected in 2020 than those who were contacted beforehand.

Even so, some critics speculate there could be a cumulative weight to 91 criminal charges the former president now faces in four jurisdictions, fueling questions about his character and electability. The disclosure of evidence and the testimony of witnesses could contain surprises. One or more of the trials could be held next year − and with that a verdict.

That would be an unprecedented collision of courtroom drama and a presidential campaign.

September: Who's out?

Eight candidates made it to the stage in Milwaukee by meeting requirements that included donations from at least 40,000 individuals and a standing of at least 1% in several approved national and statewide polls. Former Arkansas governor Asa Hutchinson was the last to qualify, making the grade just before Monday's deadline.

The debate was the first dividing line between the contenders and the wannabes. The Republican National Committee said several other hopefuls had fallen short, among them former Texas congressman Will Hurd, Miami Mayor Francis Suarez, businessman Perry Johnson and talk-radio host Larry Elder. They can continue to campaign, but getting attention and credibility could be a struggle.

The bar gets higher to participate in the second sanctioned debate, on Sept. 23 at the Ronald Reagan Presidential Library in Simi Valley. Not all of the Milwaukee Eight are seen as likely to qualify. Getting an invitation requires at least 50,000 individual donors and a 3% standing in several approved polls.

That could winnow the field, clarifying the choice for voters and giving a rival a better chance of consolidating voters who may support Trump but are willing to entertain an alternative. Most of the candidates in the debate seemed to be trying to position themselves for that opening, among them Florida Gov. Ron DeSantis, former Vice President Mike Pence, entrepreneur Vivek Ramaswamy, South Carolina Sen. Tim Scott and North Dakota Gov. Doug Burgum.

Former South Carolina governor Nikki Haley did criticize Trump for his fiscal record and called him unelectable. Former New Jersey Gov. Chris Christie and Hutchinson also adopted a more combative strategy, arguing that Trump should be held accountable for his efforts to reverse a legitimate election and to encourage the Jan. 6 rioters.

October: Shutdown showdown

In the government the Republican candidates want to lead, a shutdown looms.

Money to keep most agencies open during the fiscal year that starts Oct. 1 hasn't yet been passed, and both House and Senate leaders have said a short-term spending bill is the best way to keep the doors open while the appropriations bills can be approved. But the House Freedom Caucus on Monday released a list of demands to support short-term legislation to keep the government open called a continuing resolution, with proposals anathema to Democrats. They include addressing what they call the "weaponization" of the Justice Department and FBI, reversing "woke" policies at the Pentagon, and adopting more aggressive immigration policies at the border.

With a very slim majority in the House, Speaker Kevin McCarthy, R-Calif., may have trouble pushing a short-term funding measure through, much less long-term appropriation bills.

The Republican presidential candidates will surely be asked what they think about a prospective shutdown. Trump has often cheered on the Freedom Caucus, and in April he called on lawmakers to "defund" the Justice Department and the FBI. But some Republicans remember how forcing a shutdown has boomeranged politically against the GOP in the past, including after a record 35-day shutdown during Trump's tenure in the White House.

Defying the party's loudest voices carries risks of its own, of course.

It would be an early test of whether hardliners in Congress and their allies in conservative media are calling the shots for the GOP on policy and tactics. Another example of an ideological divide in the party is U.S. military aid to Ukraine. The Freedom Caucus has opposed additional funding for Ukraine, though Senate Republican Leader Mitch McConnell, R-Ky., has vowed to continue it.

The question divides the party's presidential field, too. Trump has said the war is not a vital U.S. interest and Ramaswamy opposes more aid. DeSantis called it a "territorial dispute" between Ukraine and Russia, though he later backtracked on that comment.

But Scott and Haley say President Joe Biden hasn't done enough, and Pence and Christie have visited Ukraine to demonstrate their support.

November: Does somebody new jump in?

Virginia Gov. Glenn Youngkin seemed to be teasing the possibility of a presidential bid last spring when his political team released an upbeat video tailored for national ambitions. "It's time to usher in a new era of America values," the narrator declared. Now, with DeSantis' campaign stumbling, some influential Republicans − including media baron Rupert Murdoch, the Washington Post reported last week − are encouraging him to run.

Youngkin, a political newcomer, got national attention when he won the governorship in 2021 in what has become a blue state. But those close to him have indicated he wouldn't enter the race until after the off-year elections on Nov. 7. Control of the Virginia Legislature, and with that the future of his legislative agenda for the job he holds, are at stake.

By then, filing deadlines would have passed for the Nevada caucuses and the South Carolina primary, two of the first four contests. The logistical demands of getting a presidential campaign organized and launched would be formidable.

In the face of those odds, if Youngkin or another candidate did jump in, it would be a sign of significant dissatisfaction with the current field, and a judgment that the race is still unsettled.

Which brings us to ...

Jan. 15: The Iowa caucuses.

When actual voters begin to cast ballots.

This article originally appeared on USA TODAY: The GOP debate launched the campaign. What's next? Five steps ahead.