When to Get Lab Draw for 'Real Numbers'?

So I have heard from 24 hours to 10 days. So say after 6 weeks you want to check your E2 ,and if your compounds are Legit’ . How many days ‘After’ last injection (Mid-Cycle) to get LC/MS/MS lab drawn. My thought would be 36hr + or = 12 hrs?? Peak not trought. That would tell you if your gear is legit . Anyone ?

I’d post this in “Pharma” not “T Replacement”.