Everyone is different. For me:
First year - every six months
Second year - every six months
Once a year after that...
Then again, knock on wood (pardon the pun) I've been < .01 on each of the tests.
I had a great pathology report but my URO told me because of my G7 grading he wants to do the PSA every 3 months for the first 2 years and 6 months after that until year 5 then once a year the rest of my life.