One ability I would love to be able to do on thumbtack is mark myself as booked on certain days/times. This is why I turned off the "instant match" feature, as I was being matched for dates I was already booked for which was a waste of $$.
An availability calendar would be a great added feature on thumbtack.
There is already a feature that will allow you to block your calendar so the instant match won't send your quotes to clients. Just go to profile, at the top right is a tool icon, click on that and you'll see calendar at the very top. Then click on the dates and times that you're already booked, the blue line will pop up, and Instant match shouldn't send you more clients requesting for those times.
I was wondering about this a little while ago too!