To answer this question, we need to explain a bit about how the current Schoolism works.
Those who are already familiar with Schoolism will know that Self-Taught classes currently run for 100 days. We’ve applied a patch to our system that will allow for flexible runtimes on classes (i.e. a subscription) but the subscriptions must be applied manually by our support staff, backer by backer. If or when this project is successfully funded, there might be thousands of subscriptions to process, so the different delivery dates are to give us time to fulfill the subscriptions in our system.
Don’t worry though, a large chunk of the money raised by this Kickstarter will go towards building massive upgrades to Schoolism to make subscriptions automatic and user-controlled.
TL;DR - although there isn’t anything being shipped, there is still manual labor involved in fulfilling subscriptions, so the different delivery dates are to give us time to do that.