El Chele, another welcome to the forum.
My uro had me with my first injection exactly one month after surgery ~ and no ill effects
But your uro may have reasons for delaying. If he won't prescribe Trimix ever, (and there is no medical reason) then you will need to go to another doctor.
In the meantime keep going with your pump. I have had excellent results with a cheapie, and three years out am still refining my technique. With both injections and the pump, you will have many failures to start with, but learn from each and never give up.