Time various from girl to girl and I say no matter what meathod you use you should say your time starts now is that alright. Usualy i would say when the money is handed off at the begining but not till then. I have had girls start the clock when I texted them for the buzz code so 15 mintus can pas before I even see the girl. I forget to clairfy time issues on occasion and somtimes as in the above case it causes conflict. Here the clock, your time ends at X should be one of the begining convos and then if you wish to go slightly over its your choice.
Personally I like sexual style songs, Poker Face from Gaga, Britney Spears, Kiss a Girl from Katy Perry, I usually bring a CD but now must girls dont have a player. It should be part of the standard package to have music lists but thats me.