The Internship depends on the state. You will have to check with the state board.
FOR EXAMPLE: In NC, you can do internship and then register those hours with the state. Their web page says, you can begin internship before you receive your fpgee certificate, but you must gain your experience in the US.
In SC, you have to have your fpgee certificate, apply to the state for an internship certificate, then start your internship and register that you are doing an internship within 10 days of starting work.
I don't know if you can apply to take the NAPLEX without your fpgee certificate in either state.