SMP Time in Service Question

So, I have a question.

If a cadet enlists in the NG prior to starting school, then starts school and ROTC and graduates and commissions as a SMP, how many of the NG years count for TIS in regard to Pay. In other words, would a newly commissioned 2LT start out with a pay scale of O-1 over 4 years. Does the NG time count one for one as TIS for pay. I know it does not count as TIS for promotion.

Thanks