When I started (t-247), took about three weeks for the libido to kick in, brain fog went away in the first couple of days.
Google "androgen receptors", you might get some insight into the biomechanics of how T is transported into a cell. And some appreciation why there is a "turbo lag" in some situations.
Like many before me, and perhaps in your case, around week two, I was thinking -- man, maybe T won't work for me, maybe I got me some bad gear, maybe something else is F'ed up.
And then come week three, holy crap! I had full-on wood, could have etched glass with it. Libido like you read about in a magazine.
Hang tight bro. I opine, help is right around the corner.