Rebirth is just a continuation of new52, it's the same timeline.
Pre52 Superman leaked into the new52 Multiverse, with wife and son, they got a series called Lois and Clark, it's like 12 issues, it's pretty good, if you want to catch up to current Superman you only need to read that one, then you can start with Supersons.
Oh and original Wally is back too, he's in the Titans, without the "teen"
But if you can't be bothered, I say wait it up, Rebirt ends this year IIRC and I'll be damned if they don't join universes with pre52.
PS: Oh, nevermind, I think if you read the Rebirth special you'll be pretty covered with everything, there will be holes here and there for you but nothing important I think.