Hi Naresh,
For your contract, the first posting (RERAPP) will be due on 08.10.2015. You can check it in your contract under condition tab. See below screen shot.
So. after your contract is activated, execute transaction code RERAPP for the 10th month in the update run mode.
Then execute transaction RERAIV with due period as 01.10.2015 to 31.10.2015
Regarding Posting date and posting period, this you need to maintain in RERAPP transaction. See below screen shot. The posting date should be 08.10.2015 and posting period as 10.