Keep same-time expiration if renew now? 30 days remaining

Thirty days remaining on my N.S. subscription, so if I renew subscription NOW instead of within 2 weeks of current expiration date, will subscription service become NEXT YEAR PLUS 30 DAYS FROM TODAY?  Or does renewing "too early" cut-off the number of days?  Meaning, still having 30 days to go, if renew today, will new expiration become  june 20, 2018 ?