Here are the current stats on PG's website regarding college commitments of which they are aware:
Class of 2015: 4,312
Class of 2016: 2,630
Class of 2017: 682
Class of 2018: 181
Class of 2019: 18
They don't list the 2020 kids, but there are one or two, I'm sure. Of course, more kids will have been offered -- these are just the reported commitments. But I think it is fair to say that the vast majority of commitments happen junior year or later.