CB Paid Subscriptions

Currently for initial price/duration usage the subscription start date is pushed using the trial_date then the initial charge is done using a normal /charge request. This instead should create a one-off invoice before creating the subscription, but still need to set trial_date. This will cause the one-off invoice to happen same time as the subscriptions initial invoice instead of being a charge + invoice you have just a singular invoice.

Note this doesn't impact functionality either way, but is the correct way to do it according to API.

https://stripe.com/docs/billing/invoices/one-off