No, there was never a point in time when someone could pluck me out of God's hand.
I didn't always know that, of course. The full realization of that fact was fairly slow in coming. But thankfully, it took root and has blossomed into a lovely certainty.
We know that Nicodemus was a believer so when Jesus said to Nicodemus "You must be born again" had he at that time already been born from above"? Remember, Nicodemus asks "How can these things be?" so he did not understand and Jesus was not telling him that the new birth had already taken place in his life; just that he must be born again.
It appears that Jesus was speaking of a discrete event, not a process.