I consider PCT to begin immediately after stopping AAS. This would mean the day of the last AAS whether injection or oral. To better understand PCT, disregard the hCG during AAS administration. At the end of AAS administration (actually within days), the T level will be about 6,000 ng/dL. It is better to use the higher estimate for obvious reasons.
At a half-life of 7-10 days, the serum T level will take approximately 4 half-lives to get to ~375. At this point, the HPTA will attempt to restart. It might be sooner/later, but this is a very good and reasonable T level. This is between 28-40 days! If you run SERMs before this time, they will in all likelihood not be optimally effective. It is also during this time that the testes will not be stimulated since the gonadotropins are suppressed. This is the best time to use hCG - during the expected decline of exogenous T (or other AAS). If you are being tested (the best method), if the serum T level is over 375 around week 4, prior to finishing the hCG, the value will represent endogenous production.