New Patrons will be charged on the day they become your patron, giving them access to all content shared with their reward tier. On the 1st of the following month, they will simply return to being charged monthly at the beginning of the month. (Now you do not need to wait for the next month to get a reward.)
Example: A patron joins your Patreon community on February 25th for $10 per month. They will be charged $10 on the day they join, February 25th, for February patronage. On March 1st, the Patron will be charged $10 for March patronage.
Everyone (new and existing patrons) will be charged on the first of the monthafter their first charge.