RP, for a while, I was corresponding with someone from OKC who had a similar rule. We wound up not meeting (maybe will at some point, I dunno), but here's what he wrote about it to me once:
"We do have one rule that we always follow. When one of us is meeting someone new for the first time, we always both meet them. ... For her that tends to keep a lot of the creeps away. For me, it usually helps assure women that I'm not really cheating on my wife. ... And yes, always the first meeting. It's not a test. Our usual method is to meet somewhere in public. Dinner or drinks somewhere, depending on what works out. And if there are any rules or preferences you'd have, I'd comply."
He and his wife have been married for 30 years and poly for about 10, so it seems to have worked for them so far. The idea of it made me really nervous, though. Maybe that's why I just never went and met them, although we did start trying to schedule something and then set it aside. But I was just starting looking at poly at the time.