The past two seasons of The Flash have always shown the audience the reveal of the villain before the team gets to witness it, but this time around could be different.
The promotional tease for “The Once And Future Flash” has a lot of clues that seem to indicate at least Killer Frost knows who Savitar really is, but with the last episode’s Caitlin cliffhanger involving Caitlin, who knows if her key knowledge is apparent to the rest of the team?
So, the short answer for when we might learn Savitar’s identity is April 25th, though that’s provided The Flash writers don’t leave us on a cliffhanger with the reveal coming even later than that; but the timing seems about right for a villain to be unmasked.