When selecting recurring gift frequencies, the following are available:

Weekly – Day – Example: Weekly on Monday
Monthly – Date and Day – Example: 1st day of every month or First Monday of every month
Quarterly – Date and Day – Example: 1st of every 3 months or First Monday of every 3 months
Annually – Month and Date – Example: January 1st of every year

How to set up a donation form for recurring gifts
How do recurring gifts from Blackbaud NetCommunity process?