A triad is a fine ideal to hold in theory, but what if one of you falls in love with her and the other doesn't... do you break it off or continue as a vee?
Great general advice here: http://www.morethantwo.com/coupledating.html
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.