Credit card processors take approximately 48 hours to clear a payment before paying out.
That charge will remain in your pending balance until it is cleared by the credit card company. You will be paid for the appointment once it is a cleared transaction, usually no more than 48 hours.
Note: After signing up and using Fons for the first time to receive a payment, it does tend to take a few days longer. ACH payments take the longest to process the first time around, usually 5-10 days, but will be faster after you have been processing payments.