You can tell your jig is on the bottom when your line goes slack and lays on the water. The weight of the jig will keep the line taut until it stops falling. Counting down is dependent on the weight of the lure. Most people use the 1 foot per second theory but again that varies from lure to lure. Unless the lure has a diving ability like a crankbait, it will slowly rise the whole way back to the rod tip.

I believe that the easiest way to control the depth of a jig is to use a float. Use a slip bobber and stop if wanting to get deep. Use a fixed bobber if going shallow.