B1/B2(Conference) to F2 COS [Urgent]

[MatrixDecoder]

I am on F-1 visa in USA doing my PhD. My gf came to US on B1/B2 visa 2 months ago to attend a conference where her research paper is published. Her travel and

other cost is sponsored by Higher education commission of our country of origin. Suddenly we decided to get married. We want to apply for her F-2 visa right

after marriage. I have few concerns:
1) When should we marry? (I have heard its better to get married after 90 days of her B1/B2 stay)
2) Would it be straight forward to change her status from B1/B2 to F2 OR USCIS can object?

(Note! She already visited on B1/B2 to attend a conference 3 years ago as well and went back to home country. We didn't know each other at that time)

Thanks a lot

[Marco 72]

Hi. This forum has only a small number of users who are familiar with US immigration. You'd probably get more answers by posting your question in the following forum:

http://britishexpats.com/forum/forumdisplay.php?f=34

(despite the name, it's a general US immigration forum, it doesn't just deal with British expats).