Should I wait till after the meet and greet to confirm the booking?

I have a couple of clients that are scheduling long vacations three to four weeks out. We doing meet and greets this weekend.

Is it better to confirm the booking asap or wait until after the meet and greet?

Pros for booking asap? 1) puts it on my calendar 2) easier to manage 3) helps the client to officially commit

Cons for booking asap? 1) Are there cancelation fees? 2) does it hurt your rating and reviews

Thanks for any an all advice