Is there a way to set up mass tasks or events?

Is there a way to set up mass tasks or events?

In my business we have over 1000 subscribers to an annually-paid service.  I am looking to setup reminders for each client as designated times during their subscription period (i.e. at 2 months, 6 months, and 10 months).  Is there a way to do this in bulk without manually adding individual reminders for each client?