Currently upgrades are instant, but we would like the option to delay the upgrade until the end of the billing cycle.

Use case:

We have annual and monthly plans, where the monthly plans are considered an upgrade from the annual because the annual plans are heavily discounted (preferably it would be considered a downgrade but that is not how Lago defines downgrades). If a user wants to switch to monthly, we want the current annual plan to finish before the switch to monthly, but existing logic does not allow us to do this.