I think a good suggestion to avoid timewasters is (and this is what I do).....
If I have a new client booked in and someone else phones looking to meet with me then I will tell him that I don't have any availability HOWEVER, I have a new client at that time so there's always a possibility of a cancellation or a no-show.
It's then up to the client if he's flexible enough to be on your cancellation list so I just take note of their number and contact them via text (with their permission) to see if they want to meet. Sometimes it works out, sometimes it doesn't.
Failing that, I just make up any missed bookings later in the week for example my cut off is 3 clients per day but I will take a 4th if I have to, to make up for a timewaster.
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