Carryforward old subscription days?

I have 20 days left on my old subscription. I have purchased a new one but if I put it in ahead of time do I lose the 20 days or is it added to my new subscription?

If you purchased from a non Norton retailer, you will lose the remaining time on an old subscription. Wait for one or two days before entering the new key to minimise any lost time .

Another option is to call Norton Support and ask them to add the time from the new key to your existing subscription.    www.norton.com/contactcs