I would counsel strongly against moving her in so quickly. A triad is an emotionally tricky situation that takes a while to settle into a groove, and putting everyone in constant contact with each other right at the beginning is going to make things more apt to explode.
<-- Great general advice for a situation like yours.
Does her bf know about you guys or is she contemplating cheating on him?
What will you do if she wants to date one of you but not the other? Would it bother you if she wants to date other people as well? Just some food for thought.
Also, I would say that in any new relationship, dating before things get serious is a good idea. Probably moreso in poly, because the dynamics are more complicated. Take it slow.
The major players. Me, 30ish bi female. Gia, girlfriend of 4+ years. Clay, boyfriend/dom. Davis, ex/friend/"it's complicated." Eddie, roommate & fwb.
The supporting cast. Eric, Gia's husband. Bee, Gia and Eric's toddler. Dexter, Gia's lover. Helen, Eric's lover. Izzy and Nikki, Clay's partners. Liam, Eddie's husband.