1.The best way to help on this is to take all first 60 sec when the game starts and then be random as it is now.
2.One more think to help some problems the screeshots it tales at same hour it will be in the same file
Or detect when the code /name is used on cmd of the game.
Example
1. If he start the game at 16:00 the program should take at least 1 screenshot per 2 seconds till it be 16:01 (60sec.)
2.If a player start the game at 17:30 and close and then open at 17:39 the screenshots are saved in the same rar file.