This is a new feature for Patreon! Basically this just means that if someone new pledges in the middle of the month, or if one of you decide to edit your pledge to a higher one in the middle of the month, I will be paid right away instead of having to wait till the next month. It's a safety measure for me so that someone wouldn't be able to pledge a high amount, receive their rewards, and then drop their pledge at the last minute.
(I don't think anyone's done that with me, but I think it makes things a bit more streamlined for everybody! If someone wanted to donate just one large amount to the cause, for instance, they would now be able to do that without having to stay pledged for several months before being charged.)
You can read more about it here, and please feel free to ask me if you have any questions or concerns!