Each companion has her own policy, but most like the donation beforehand so that they don't have to worry about shenanigans. Please understand that a few bad apples sour the whole barrel and make ladies leery of waiting, but I understand that Hobbyists are nervous about paying up front and then getting played in an unpleasurable way. Seeing reputable, well-established companions may assure you that they will follow through as promised.

My regulars take care of it afterward as we are comfortable with each other, but I prefer gents new to me place the donation on a table where I can see it shortly upon arrival, and I find a way to surreptitiously check it. I haven't had near the problems some lassies report, but yes, I have been shorted on a couple of occasions, my own fault for counting after the fellow left.