Hmmmm....The ladies may answer this better than I, but I would ask her after going down on her. Thats how it always works for me or I'll bring up the ole 69 question. If you are making her cum like crazy when you go down on her she should have no problem giving you a Blow. My gf automatically goes for my cock after I go down on her(gotta make her cum though).However, there is a small % of chicks out there that do not give head, so you may have one of those.