There are times when you may get a friend request on your facebook account from a person you don’t know, but he or she may have a some mutual friends with you or the another facebook user could be a total stranger.
At such times you don’t want to confirm that friend request and also don’t want to ignore the request, Facebook now allows you to select Not Now option which actually can delay your response about that friend request and this way you wont see this friend request popping up on your facebook profile page.
Not Now button moves those requests to a state of limbo, in which you can come back to them later and accept or block the user. The ignored user will not be notified, and they can’t send you another request while it’s in this pending state.
This feature seems to be pretty useful to take action on some of the friend request for which you need to take a thought before you accept or reject it, must say nice feature introduced by facebook., thumbs up