how to calculate time interval between player move and AI move

Hii, I want to calculate time taken by the player for making his move. My player can pick his coi开发者_开发知识库n and make his move to a box(like in chess). If my player pick his coin early but make his move very lately, then how to calculate time between AI and player move

One option is to reset/abort the move action if it is not finished after a certain amount of time, say 5 secs or whatever is reasonable to your game.