I mean, you CAN fit it in with a 15 year timeline if you jiggle a bit: Dick being Robin from year one of the age of heroes to like being 18 at becoming Nightwing 7-8 years later, Jason becoming Robin then blowing up the same year as Nightwing's debut, Tim being Robin for 4-ish years after, and Damian debuting as Robin a year before the "present" (since Superboy/Kid Flash III/Aqualad II are all definitely really REALLY recent developments, timeline-wise).
Time has just enough time to be established as regular Robin for four or so years from 13-18 years old in that 15-year timescale the pre-Flashpoint world was, and can even be in a 10-12 year timeline.... it's just you have to condense HIS history to allow Dick's vital development and Damian the inevitable time to play out as the newest Robin.
It's workable. Surprisingly. No, really, I can see it based on what they say are current ages and when each Robin's age was pre-Flashpoint. But it's the FEELING of condensation that makes Tim suffer compared to the others.
It just feels *off* for more than two Robins in the usual timeline scales superhero media use, and it's telling non-comic media focuses on just one successor to Dick be it Damian (the new DC animated movie-verse), or Tim (Arkham games, Young Justice, etc.) since Jason can always go boom really early enough in his tenure not to be a problem.