It's now possible to configure an email notification for your customers who are setup on recurring subscription payments (Membership Plans).

It was previously not possible because of the Stripe payment gateway features but they have now added the feature.

By default they reminders are currently turned off. To turn them on go to your "Signup Settings" page from admin menu. Under the payment notifications heading turn on.

The number of days to send the email prior to when the subscription will be charged is configurable directly inside your Stripe account. The default is set to 7 days. 

You can configure it from the Subscriptions - Settings section of your Stripe account.