Hi @Pat99,
Great idea. I have seen it a lot on this forum. Right now it is not possible to set up your availability this way. I agree, though, it should be. Sometimes you can have someone at your place on a given date, but could not be there to meet them on the same day.
My recommendation is to post this on the host forum. This is a forum where people can pitch ideas directly to the company. If it gets enough likes or comments, it will be flagged for review by the company. Better yet, look for this idea already on the forum, and give it a comment/like. Also, post the link here for others to see and add to.
No guarantees, of course, but it has happened that some changes have been made in the past due to this...