I would choose a few who I like and go in sequence. or contact a few at the same time and then whoever responds in a timely manner, I proceed with. Timely as in within an hour or two. I get they are busy or may have a client whilst I contact them.
Those who don't respond, or respond after a two days or more, i discard mentally. Unless they give a reason why, or seem very apologetic. Users should respect escorts, of course, but such respect is two-way.