Kelly Ann made it pretty clear Trump will announce next week.
I suppose then that if Merrick Garland is going to indict him (for misfiling stuff?) he has to get in front of Trump announcing and drop said indictment on Monday. I'd guess that's the thinking, do it before he's a candidate. However there is no getting past the appearance (obvious glaring appearance) of partisan pollical motives, whether he does it prior to or after Trump's hypothetical announcement.