I had a fellow offical tell a clock operator that on a missed free throw (1 and 1 or last free throw) that the clock is to start when it is touched. I have told the clock operators that the trail will signal (with the chop) when they are to start the clock on a missed free throw. When they ask when is that, I say that it is when the free throw is clearly missed (is under the rim); but not to determine it for themselves, just to watch the trails arm. Who is correct?

Well...
 

you both are, kind of. Yes, the clock operator should look for the ref's time chop. However, we wont signal for the chop until it is touched by someone. The timekeeper should look for the chop, however, IMO I think most just start when THEY think the ball has been touched.