To most people, "kicking in" is when they get their biggest pumps in the gym.. For a given cycle, this occurs maximally when (total, accumulated) blood levels are obtained. Depending on the AAS, this can be a week or two (dbol, fina, etc..) to a month or more (deca)..
Now, after an injection, the RATE of steroid released/second is greatest immediately because the RATE is proportional to the size of the depot. Think about a bucket of water with a hole in the side. The more water in the bucket, the faster it flows through the hole. When the water level gets lower and lower, the rate that it flows through the hole gets slower and slower. This is exactly how an ester injection depot works, only the ester leaks out over time, is de-esterified (activated). Once the steroid is activated, it's half life is very short-- hours.
So, imagine a single injection, like a bucket of water. Before the bucket is empty, another injection- bucket of water is set beside it. So you have two depots, the first is still releasing and contributing to over-all (active) blood levels as is the second, only the latter is releasing at a faster rate, of course. Now you can see that the two injections together give rise to a greater over-all level of (activated) testosterone blood levels. After more and more injections are administered, the blood levels get higher and higher until they reach what can be thought of as MAX possible circulating blood levels of androgen for a given dose/week. Mathematically, there is no such MAX, per se, blood levels do keep climbing on a constant dose, but at smaller and smaller amounts. When the constant dose cycle has reached this "leveling off" point, this is essentially the MAX blood levels for that dose.
SO you can see that test levels peaking 24hrs after an injection, and the test levels after 30 days or whatever are two different things..
Feeling the Anabolic Androgenic Steroids (AAS) "kick in" is psychological as well as physical.. If you could instantly jump your blood levels up to the MAX for, say, 1000mg/week testosterone enanthate, you would have the blood testosterone (active) levels that would be obtained after a good month of constant dosing. (This is a front load, by the way)
But that doesn't mean you would FEEL the same as the guy who took 30 days to get there. The highly quantitative assey to detect "kicking in" of the Anabolic Androgenic Steroids (AAS) is feelin' the pump.. And this actually is not completely related to muscle growth. What I mean is that feeling a bigger pump than a week ago doesn't mean you're gaining more muscle than a week ago...
Got it?
Andy