To be fair, aside from playtime, a Day 1 player (and I mean day 1 as opposed to just early player) doesn't have a significant advantage since most of the mons available from Day 1 either were more novelties (Mew) or have since come back (the Rotom forms). I'd say (if I'm remembering the event order right) Kyogre was the first really significant "timed" event that has yet to return, and it's reasonable enough to substitute (things like the current Manaphy, Swampert, etc.).
Heck, even the Day 1 time didn't give a significant advantage if you were like me and didn't know about Meowth grinding until almost a month in.
Heck, even the Day 1 time didn't give a significant advantage if you were like me and didn't know about Meowth grinding until almost a month in.