Our Monthly billing run is 16 days before the invoice due date.
In the even of a 30 day month, the invoicing runs on the 15th and a 31 day month, invoices run on the 16th.

All invoices are due by the first of each month

Package Changes: All Package changes can only be done before the billing run, all connectivity downgrade can be only done with a calendar month notice. Upgrades can be done before the billing period.

Ownership Changes: Ownership changes can only be done before a billing period, once the billing has been run, the ownership cannot be done with an outstanding invoice