Something Patreon I guess should add somewhere. @reyna
If you join on a day like May 31 or June 1, 12 am EST which is May 31, 9 pm PST, you are still paying for May. If you join on June 1 (after 3AM EST) (that is 12 AM PST) you will be billed for June.
I noticed that time matters when a patron joined April 1 at 12am EST, canceled the same day, and was only a patron for that one day due to the time she joined. Since Patreon is based in California (PST) it works on their time.