I made all of my reservations between 11 PM and 12:05 AM., but I was well inside my 90 days.
Unless you’re bucking a 90 day headwind, you should have no problem.
If you are just having your 90 day window open tomorrow, you could try just after midnight. Just keep in mind, that it took me an hour to make 10 reservations, so you could be up until 1:20 checking e-mailed confirmations and printing them out.
The only reservation I made at 90 days was Le Cellier, and even then, I could only get a dinner reservation for the 93rd day.