Yikes, this thread got busy!
I asked as pinning the same site without allowing adequate time for both the site to heal (you are causing trauma by cutting the tissues) and for the depot to disburse can cause issues with scar tissue and potential abscesses to form.
It is typically recommended to allow two weeks before hitting the same site twice. So, if you're injecting twice a week, four sites is good, but six would be better. I use 8-10 personally as I learned the hard way about scar tissue, so I'm kind of anal about it.
Spotinjections.com has some pretty good images showing multiple sites you can choose from, although I advise staying away from biceps/triceps/calves until you're ready to possibly deal with some serious PIP.
Oh, and delts will vary from person to person as it's the size of the little guys that ultimately determine how much oil they can take. Most folks can work their way up to 3cc, but 1cc is plenty when starting out.