What determines the first process date if someone signs up online?

When a club member signs up for a subscription membership from your website, their first shipment will automatically be scheduled 2 days from their sign up date.
For example, if someone signs up for a subscription club on November 30, their first shipment will be scheduled to process on December 2. 
All subsequent club shipments will be scheduled for the 2nd of the month for the frequency chosen. 
Commerce7 - 2020-11-30T152551.622If the 'Next Process Date' is changed on the club membership the scheduled shipments will also change. For example if we change the the 'Next Process Date' from December 2 to December 5, all future shipments will be scheduled to process on the 5th of the month. 
Commerce7 - 2020-11-30T153419.397