I Guess you are using RSEINB00 to create IDOCS from file.
Change the partner profile in WE20 for the partner and message type ORDERS to "Collect IDOCS" instead of "Transfer IDOCS Immediately". This will create IDOCS from file after RSEINB00 has run but the IDOCS will be in statsus 64 . Schedule another report RBDAPP01 to post these IDOCS in background .
In the job you can define First step as RSEINBOO and second step as RBDAPP01.