Start Clock?

[Tom Cook]

Friday night we had a pass by A, which was intercepted by B. B, however was called for roughing the passer and interference on the play. A accepted the penalty and during enforcement the referee looked at me and said "clock starts on the snap, right?" I concured and that's what we did. The coach on my side was yelling for the clock to start on the ready. I told him that there had been a change of posession even though his team didn't get to keep the ball and the clock had to start at the snap. Does anyone here disagree?