My experience has been all over the lot, from an answer within minutes to a response days later. I never fault a guy for not responding for at least a few hours, when you factor in other clients on the table (you don't want him texting while working on you, right?), going to they gym (you do want him to look good, right?), other jobs, and such. I often can't schedule very far in advance, but that's on me, not them if they can't respond quickly that day. I know I'm taking my chances.