I've only got my own experience, but I can't be that different from you.
I've fronted both Test-E and Deca and they still take 4 weeks to kick in. Why is this? It must mean it's not about reaching maximum blood levels asap, but something else is going on.
I imagine if I hadn't fronted it would had kicked in 1-2 weeks later. So I will continue to front for that reason... but still... why?