Hello.
What is the right thing to do if u are FJ on a competitive tournament and u see that two players startede their match before the HJ anounced that they could begin?
a) Tell them to scoop their cards and restart the game when the oficial time is going on, or
b) Tell them to stop playing till the oficial begining of the round.
c) Other options?

I don´t find this situation covered in the MIPG, so I supose that we should caution those players. Is it right?
Thanks a lot for your help.
Cheers,
Javier.

I'd just tell them to wait until the clock actually starts. Like you mentioned, this is not a specific infraction so there is no penalty.

Having them restart the game is such a big feel-bad with no real benefit.

I would just let them know that the clock has not yet started, and have them pause their game until it starts, as well as cautioning them to please pay more attention to announcements.

Already a thread on this.

http://apps.magicjudges.org/forum/topic/9869/