arvindkgs-schedules

[astral monolith]

To start off - you'd add a Schedule to the Subscription (which you can see how to do here https://stripe.com/docs/billing/subscriptions/subscription-schedules/use-cases#existing-subscription)

Then after creating the coupon you'd add an additional phase to the Schedule you just created with phases.coupon set (https://stripe.com/docs/api/subscription_schedules/update#update_subscription_schedule-phases-coupon)