When I started out, I tried to schedule at least a couple of weeks out. Often it worked okay, but with a significant number of ladies, they would just ask me to get back in touch a day or two before I wanted to meet. I also noticed that a lot of ladies did not set their schedules, announce their incalls, or put up their ads more than a couple of days in advance, so I missed seeing some ladies I wanted to see.
So I rarely schedule more than a week ahead, except with my regulars, and often schedule 2-3 days ahead. I do not like scheduling the same day, so if a lady asks me to call her that day or the day before as she will not know her schedule before then, I take a pass. My schedule does not work that way.
2-3 days ahead seems the norm, for the whole world, but obviously there are a bunch of ladies and gentlemen who are quite last minute.