IMO, it should start in about 1 hr. About the pain, I never had that much pain with it. I also injected it into my shoulder. when doing 1cc, I'd split it into 2 injections, in a 25ga X 5/8", one for each shoulder. I would draw it up with a 22ga needle and then change it over to a 25ga. Worked good and I was doing 100mg EOD.