Nothing helps prop pain. I figure it's sitting in there waiting to do it's job, why not get some blood into the area to start picking it up and moving it on it's way? Actually, yes, I do experience less pain by doing it this way.
The only thing that matters is that you shoot up at the same time every day (or e3d or eod...etc.), the actual time makes no difference. If your using short acting esthers (test prop, tren a) then it's important to shoot up about the same time e.d. That being said I usually take my shots in the evening around 5 or 6. I don't have time in the morning and am too tired before bed. When I get off work/school is the best time for me.