It depends on the Patreon. I signed up to one a few months ago and I had immediate and full access to the whole page but wasn't charged until the 1st of the following month.(ETA if I understand correctly from reading their truly awful trustpilot reviews, Patreon pulls cash from you on the day you subscribe, but regardless of what day of the month that is, pulls your second payment from you on the first day of the next month, so if you subscribe on 29 Jan, you’ll have money pulled on 29 Jan and 1 feb too. Don’t take this as fact until clarified by Patreon expert fraus. WARNED.)
Patreon offers several billing options: