The counters all reset automatically and the clock starts ticking as soon as the input starts. Everything stops when the input stops. The pole at the right carries `T`, the current runtime in ticks, and `U`, the last tick where output wasn't keeping up with the expected rate, and some internal bookkeeping. Should be pretty easy to wire that to your lamp display or some nixie tubes. This works off a single segment of each belt, and the compression detection works off pulse reads, so there's no delay on compression detection.
(edit: whoops, the ratio I gave above for redbelt throughput's wrong, 9 slots at 2 slots/ tick means you one item per lane per 4.5 ticks, so make the numerator 9 not six and the denominator -2 * lane count for red belts, since you can't dial in 4.5 for a numerator. 3 and -1-per-lane for blue belts and 9 and -1-per-lane for yellow belts are correct)