Due to the size of the game, it does not wait for over players to “finish there turn” in order to continue the game. Instead a turn is based on a tick rate defined by the server.
Therefor , a “turn” is considered to be finish every time the tick-rate timer arrives at 0.
Somme actions, events, units do have turn based limits, overs do not.
The tick rate is viewable in the “about this game” pane. The standard tick rate is 1 turn every 15 minutes.