You can disable the 'Auto-confirm Memberships' online signup setting here (navigate to Admin> Online signup). When this setting is disabled, patients will still be able to complete your online signup form as usual, however, they will be created in your account with an 'unconfirmed' membership status. They will not be billed and they will not be an active member until a user of your account manually confirms the membership in Hint. You can clarify that you currently have a waitlist on your website before the patient is redirected to the online signup page, as well as in your online signup confirmation page message. Then, you can confirm memberships for these patients in the order of their 'Joined Practice' date in the future.
Note: Please notify Hint's support team to be added to the 'Waitlist' feature request in our feature forum. You will be notified of any updates if we decide to move forward with this enhancement.