There's really no reason to start HCG on day one as you're not suppressed yet. Best time is round 2 weeks in. I prefer to run on cycle but others do like to blast for 10 days at the end. One keeps the boys awake for the full cycle, the other lets them shrivel up a bit, but gives them a swift kick in the nuts right before post cycle therapy (pct) starts. Either way, your post cycle therapy (pct) will be more effective and start working sooner if your testicles are at full volume, so any HCG is better than no HCG. You want your last HCG pin to be 4 days before you start Human Chorionic Gonadotropin (HCG), so if you only have one vial, count backwards to find your start date. The timing of the last pin is more important than that of the first, so if it works out that you need to start at 4 weeks to end 4 days before post cycle therapy (pct), do that.