The reason I believe CA non-owners will be first in priority is two reasons:
1) A large concentration of reservation holders is in CA
2) It is a heck of a lot easier (and quicker) to deliver cars in CA, since the factory is there.
I am not coming to this conclusion because I am in CA. This is thinking logically about how Tesla operated in the past, and how it will best get their delivery numbers up.
Your first reason should be that Elon said that they will start in California. Then again this was based on the ramp taking until 2020 to reach the 10,000 per week.