roker, as far as I know you can get married whenever you want and even file I-130 before your

GF gets her naturalization certificate and you will have to wait down the line to get your greencard, but as soon as your wife gets citizenship

your case will be current and you will be interviewd pretty soon. It takes 3 years to be eligible to apply for your own citizenship after you get your green card through marriage.

Gud luck