Most booking complaints trace back to hours that were never written down properly. The client booked a slot the salon cannot honour, and the apology costs the visit you were about to earn.
Define the week first, day by day, including days you close entirely. Those hours drive both the public booking page and the internal diary, so a client can never see a slot the front desk cannot staff.
Then handle exceptions early. Public holidays, a training day, a stylist who takes leave: block the slot before it can be booked rather than cancelling afterwards. Leave requests should be part of this, which is why staff ask in the system and the manager approves in the same place.
Finally, publish the hours. Opening times on the contact page, the booking form and your social links should all come from the same weekly schedule, so the answer a client gets is always the same one.