Weekly content dripping and monthly payment

I've got a membership site dripping content weekly that is setup as follows:

week 1 - £24.99
week 2 - £0
week 3 - £0
week 4 - £0
week 5 - £24.99
week 6 - £0
and so on...
then it becomes recurring after all content's been delivered.

I'm advertising £24.99 monthly, but I'm concerned that subscribers may expect to be charged on the same day of every month and instead they will be charged every 4 weeks.

Just wanted to check if there is a way to make sure the subscription is actually charged monthly and not every 4 week, or does this happen automatically with a setup like mine?

Thanks