How long should PCT last after a testosterone only cycle?

[alienboy]

I am starting a 350mg test only cycle for 12 weeks and I've read about how to use aromasin and hcg on cycle and even how to use nolvadex and clomid during PCT but i can't find anything on how to know if your PCT should last 4 weeks or 6 weeks. Also after getting blood taking a few weeks after PCT is finished if my Testosterone and estrogen levels aren't back to normal do I start back on nolva and clomid again? Thanks ahead of time for the responses