Dosing depends on how many IU you are taking. I have read if shooting 2IU at a time, then do in one dose, maybe 3IU and definitely 4+IU shoot split up dosages. If doing 2, optimal time is 14 hours after your bed time. For example, if you go to bed at midnight, shoot at 2pm. Reason being, your body starts to produce its own HGH about two hours into sleep, so then you try to inject dose 12 hours after that to keep highest sustained levels of HGH in the body. I've never done more that 2IU per day.