I agree with
@wondering that plasma levels of testosterone should start rising very soon after an injection. I'm going to diverge on the question of when the peak occurs. I suspect it is most likely in the range of 2-8 hours post-injection, and almost certainly in under 12 hours. I base this on research, theory and my own results.
In particular,
some work by Behre and Nieschlag is already consistent with peaks occurring in less than a day for propionate and enanthate. Here's the curve for enanthate:
View attachment 9255
The theory is easily illustrated with the simple bi-exponential model. There are two parameters to set: the half-life for the absorption, something like five days for cypionate, and the half-life for the elimination of testosterone in serum, which is estimated to be in the range of 10-100 minutes. For the latter, I'm partial to a figure of 30 minutes, but even if 100 minutes is used the peaks still occur in the first few hours. Here's a sample I ran for propionate with a little different model for absorption, but still with an apparent absorption half-life of about 0.8 days, and T usage half-life of 30 minutes. This is a step further, summing results to show what each day looks like with daily injections.
View attachment 9256
My limited measurements with daily propionate have at least been consistent with this model. I had taken several trough measurements, coming back in range of 300-500 ng/dL, depending on dose. Based on these I predicted a peak of roughly 1,100 ng/dL for a particular dose. Then I took a measurement at two hours post-injection, which was 1,000 ng/dl. While this single measurement is not too meaningful, it at least supports the idea of a rapid rise in serum testosterone.
I just recalled that
@bp recently shared similar results
here for his daily propionate injections.
Protocol was :
70mg/week (propionate) ED injection (10mg /day)
Bloodwork was mental tbh.
My daily deviation was massive.
TT:1100 (at 10.00, 2 hours after pin)
TT:350 (08:00 , 2 hours before pin)