I am looking to use Zoho for a small magazine business (physical and digital).

I am already four editions (quarterly) in with approx 800 subscriptions that are about to roll over / require renewal. 

I need to be able to: 

> upload all 800, categorise by period (i.e. 600 are due to get renewal emails, 100 are one edition away, 200 are two editions away etc). That is across the database they are at different stages of subscriber timing.  HOW CAN I UPLOAD the 800- current subscribers, dictating here they are in the subscription cycle, and set the system up to then send email reminders to get those subscribers coming off to resubscribe via Zoho?

The way I see it I have to do this individually for 800 subscribers !!!! IS there any way to mass upload backdated subscriptions? 

Thanks you