You should easily be able to get 100 scrolls per month if you spend occasionally on lucky star wheel or lucky board. That, together with free pulls(100, 25 rebate, 30 free) should give little over 13 months instead of 28. You need to be really active and only use those scrolls during rebates though. After you finish medium refining it goes even faster, since you redeem scrolls instead of refines in monthly.