If we know time that ball will take from our prediction moment to drop, we may up ply same time for rotor in the beginning of the spin. How it's done?
Look where zero is, start time... at the end of the time look wich number is at the place where zero was. Distance between zero and number we observe at the end of time upplied will be indicator of offset we need to add to our visual key.
If we use half time , we need to multiply that distance by 2.... ets