It doesnt matter where you get married. Get married first, ask your spouse to file i-130 for you when she gets back to the States. It takes about 6 months to get i-130 approved. Luckily, the applications are only backlogged for a few months for gc holder's spouses. After i-130 approved, it takes about 4 months to complete the rest of the process. You will be in the US within a year if there wont be backlogs. All d best!