My guess is tomorrow or Wednesday. If you read between the lines, you can tell that his recent statements suggest that he's on his way out. Well, he's probably not done with being involved in this race, just that he's done campaigning as a candidate.
Yeah he hasn't done much this week to get under my skin. Apparently he gave a speech today or yesterday saying he was going to take it to the convention? But I only know that because someone posted a link to it on Facebook with the typical stupid caption, didn't hear about it in the news at all.
He needs to get out though, the race can't really start until he's gone. Hillary's already running full sprint but it's like she forgot to tie one of her shoes or something, just not the complete experience until Bernie's officially in the ground and not threatening to stir up even more primary sh*t in the middle of July or something.