Late May seems ... kind of late? I was listening to some qualified people talk about March as a reasonable time frame, both for the defense to prepare, and for the trial to wrap up before the election. Having it in May means that the outcome of the Republican primary will probably be known, very possibly with Trump as the presumptive candidate. Which then allows the defense to yell about "b-b-but presidential candidate, you can't hold him responsible for anything!"
Well, we've already seen that that "logic" applies when Step 2 is "Become president." That precedent was already successfully set; might as well try to wedge it open further.
Keep in mind that this is a Trump appointed judge and she's essentially all in on the Trump train. There have been articles in the past month or so speculating what she'd do, whether push this off until after the election (which is what Trump wanted, and if he won, he'd make sure it went away or got buried, and would basically destroy her reputation as a credible judge, so that would play into her career) or have it before the election, which is obviously what Trump did not want. I think she's splitting the difference here, having it before the election, but months after what Jack Smith had requested.
FTA:
In an order issued in Ft. Pierce, Fla., U.S. District Judge Aileen Cannon says the evidence in the case is "extremely voluminous and will require substantial time to review" and includes classified and top secret documents that require special handling procedures. She also says the case meets the legal definition of a "complex" case, requiring a more extended trial schedule.
This sounds like she's trying to appease both sides as much as possible with minimal damage to her credibility, reputation, and career.