When are drop off points calculated, pick up or drop off?

My understanding and experience has been that even if your ride extends into another 15 minute block, the points are awarded from the map as it was when you started the ride.  Sometimes when you're close to the end of a 15 minute block, say 8:14, you may have indeed unlocked the bike at that time, but sometimes the system doesn't acknowledge the ride starting for a few more seconds (sometimes 30 seconds).  Then it would kick you to the next 15 minute block map.