if maintaining your body's natural ability to produce test is of any importance to you, the only way to answer your question is through blood work. ideally, one would get blood work done before they start a cycle to see what their natural numbers are. then, after your cycle, PCT and some time off, get your values taken again to compare them to the previous numbers. this would be the only true way of knowing. unfortunately, many guys dont do this. 

the internet can be an amazing tool to learn about AAS but it can also be misleading. there is a lot of misinformation out there. i've seen it posted time and again, "time on plus PCT equals time off". this is a guess, at best. there are a lot of factors that go into how long it's going to take someone to recover. i find that long esters take longer for me to recover from. i believe it's because the active hormone builds up quite high and lingers for some time. 19-nor's, like tren and especially deca, can be very hard to fully recover from. age plays a huge role and so does genetics. and just because you "feel" normal, does not mean you are recovered. i was recently working with a guy who felt fine 6 wks after PCT. he said that maybe he was still a little sluggish, but overall, felt good and his sex drive was normal. he went in for labs and it turned out that he had the test levels of a teenage girl. so go figure! 

if you want to speed up the process, i would suggest HCG during cycle. it's made a big difference for me. that being said, there is no magic PCT formula. we all just have to tough it out and get labs to make sure we're back in the normal range. if you dont have a dr that is cool with what you're doing, i'd find a new dr. there are also services online that are discrete,