Same as the other 3 posters, apart from the googling images thing - I can't even begin to imagine how to do that, it's totally out of my comfort zone and level of expertise. If, OP, you also mean it in the sense of deciding when you get there or just before (say she doesn't reply to calls tor texts just before the punt) I sometimes have a back up plan. That doesn't mean booking another girl, that would be dishonest, just having a few other phone numbers handy in the general area or I might mindfully accept that I could be going home without doing any punts at all - leave that option open. Actually, on the 1st strategy I've had some very nice surprises, including, instead of seeing the legendary Zizzi, who was suddenly not free (excuse, landlord painting flat - real reason; regular had turned up and was giving her all the money instead of robbing agency taking a 3rd) and got Emma instead and wow! Was I happy about that!