A day or two at the most, really I dont like to do it at all. I like ripping open the sterile syringe and needle each time, using it immediately and then pitching it. Guess it just makes me feel better. You are probably ok though.
I used to preload for a day or two ahead,but forgot a syringe full of 1 cc sten and 1cc brovel prop for a week and the rubber plunger was swelled big time had to throw that one away
The plungers are made of med grade silicone and not rubber. AAS should have no effect on them. L2R may have had some kind of other problem...I am not saying that it is not true...but the AAS still should not effect the plunger