Depending on the size, I feed mine once every 7-12 days. Twice a week seems borderline powerfeeding, something I personally wouldn't want to do. When you get your boa, do what you deem best.
:Ok, i should be getting my new baby BCI girl in 2 days. I was talking to the breeder, and he said that he's been feeding her two pinkies a week, but that she really only needs to be feed once a week. I was wondering should i just feed her once a week?