Assuming / hoping a response is coming, I see one important reason to delay, aside from Military administrative preparations..
It is easier for India to take harsh measures like Suspension of IWT, expelling Pakistanis, or passing some anti Pakistan legislation before retaliation (when only Indians have been killed) than after retaliation.. when we are also the aggressors..
So, if GOI wants to ride the sympathy wave for some quick moves locally without political opposition, the month after the attack is time..