Either way, you want to use an insulin pin so doing IM is really easy with HCG. I'd just stick it in your delt or tri. Not a big deal at all. Little trama to the muscle. It's nothing like doing an IM shot of oil! I'd prefer IM, but sub q will work just fine, if thats what you prefer. And yes, always use Bac water vs the sterile water that is sometimes supplied with your HCG. Your plan sounds good. If you have enough, I would run it right up to about 3 days before you start your PCT.
Also, I would use a small dose of AI on your cycle