If this is your first time to withdraw then Patreon will hold your payment for 5 days from the date you added your payment or received payment. Your payment will also be put on hold for 5 days if you update your payment method or tax details.
Most of the time, some new accounts are subject to checks and holds. It is something that should not worry you unless it takes more than a month.
If there is any suspicious activity detected, your withdrawal will be on hold until the review period is completed. You may receive an email from Patreon support requesting verification documents.
If takes more than a month without hearing from Patreon, you can email Trust & Safety at firstname.lastname@example.org.