We must first determine the time between spins.
The time needed for each spin, depends heavily on roulette table activity and dealer style. If the table has many active players, it takes more time for them to bet and then it takes more time for the dealer to pay them off. Some dealers wait a long time for players to lay their bets, while others wait less.
I would say that in a very low activity table each spin can take less than 3 minutes, while in a high activity, very busy roulette table it can take more than 6 minutes between two spins.
Let's say that in a "medium" table a spin takes (very roughly) around 4 minutes. This means that it takes around 400 minutes, or more than 6,5 hours to see 100 spins.