Hi Shashidhar,
the sending to ERP is configured and done on the OD (outbound delivery) and not on the ODO (outbound delivery order).
This is one main difference between the inbound delivery and outbound delivery order, that there is one additional object.
Therefore a sending is done when an OD exists.
So in principle the sending is/can be done before GI if you create an OD manually. But typically GI and OD creation are done in one step. Manual OD creation is usually not done (as it is an additional step).
Best regards
Markus