Scheduled Subscription Plan Switches (End of Cycle)

I want to be able to schedule a subscription plan switch to occur at the end of the current billing cycle. Currently, all update_behavior options (proration-charge-immediately, proration-charge, and proration-none) cause the plan to switch instantly in the system. I need a way (e.g., via API) to allow a user on a yearly plan to switch to a monthly plan where the yearly plan continues until the end of its term, and only then does the monthly plan and billing become active.