I would expect to see Bryce Harper, Machado, and anyone else of interest from this year's draft added once (if) they sign contracts with their clubs. Last year they added Strasburg and a few others when they signed.
As for Perez, I don't know. One would think he would already be in the system, but if he doesn't make the club or at least make noise about a September call-up then they don't have any reason to add him. But who knows with ESPN, they're maddeningly inconsistent. Their company line is that if they're projected to make the opening day roster they'll be in the database, if not, they'll be added the day after their first appearance. But then you see that Mike Trout is in the system for some reason and they break their policy for Pineda and it's like the left hand doesn't know what the right one is doing over at ESPN. I had a bad experience of watching Andrew Bailey start the year with SP eligibility only to watch it get taken away (after keeping him over Choo and Strasburg) and having been one of the people to inquire about Pineda, I'm done with ESPN after this season.