the benefit to waiting is that you get more xp per play/training session at a lower level. xp stops in the playoffs so that, combined with the games meaning more, is the optimal time to boost provided two things,
-that you get enough playing time (~40ish snaps)
-that your team will make the playoffs without you boosting.
i dont know how many plays you get, if its near 40 then yer good. we shouldnt have any trouble making the playoffs so.. you should be good on that front.