Step 1 :
From your admin console go to "Billing and Payments" select "Create Invoice" and Enable "Recurring Plan"
Billing Interval :
Monthly - Every once in a month a invoice will be sent
Bi-Weekly - Every once in twice a week a invoice will be sent
Weekly - Every week a invoice will be sent
Step 2 :
Due On :
The due date for the invoice
Invoice On :
Date on which the invoice you need to send .
Plan Start Date :
Plan Start date means the plan recurring start date.
Plan End Date:
Plan End date means the date at which the plan needs to be ended.