Is it possible to select or change the billing date of a monthly donation?

Monthly donations are billed on the same day they are started.

It currently isn't possible to schedule in advance or change the date of a monthly donation.

When a donor starts a monthly donation on your Zeffy form, that sets the date on which their payment method will be charged every month. If they wish to change the date they are billed on, the monthly donation can be cancelled and started again on the date they want to be billed on. 

To cancel a monthly donation, a donor can do it from their Zeffy donor account (see how here), or the organization can do it from the Zeffy account (see how here)

To learn how to set up a form with a monthly donation option, click here