How variable revenue scheduling rule to be used from OM to RMCS along with duration

We have requirement to recognize the revenue 40% upfront and remaining 60% based on duration of the subscription. duration is not known upfront so we are using variable revenue scheduling rule and defined 40% on first period and based on the number of duration in month RMCS is generating the revenue for rest of the month dividing equally.

In our case Revenue scheduling rule is flowing from OM to RMCS but not the number of duration. can you please help to confirm if we are missing any setup or what field to be used in OM so that number of duration can be interfaced to RMCS and subsequently from SMC as well.