How are shots counted, and when can we start measuring?

From the Laws of the Sport of Bowls (Crystal Mark 4th edition):

• A shot is each bowl nearer the jack than the opponent's nearest bowl (law 22.1). No bowl may be moved until both sides agree whether it is a shot (except to measure another bowl).
• Don't start too early. Counting starts only when the last bowl of the end has come to rest, or 30 seconds later if either skip (or opponent in singles) asks, for example to see if a leaning bowl falls (law 23.1). Bowls likely to fall may not be secured during that 30 seconds.
• Measuring before counting starts costs your side the right to play any bowls you still have left in that end (law 23.3).
• Measure between the nearest points of the jack and bowl. Use a flexible or string measure where one of them is in the ditch (laws 23.4, 23.5).
• If a bowl falls on its own during counting, leave it, and shots already agreed still count (law 23.6.3).
• No shot (tied end): if each side's nearest bowl is touching the jack, both are equally distant, or there are no live bowls on the rink. A tied end counts as a completed end (law 24).
• The last player in an end may choose not to play their final bowl, but must tell the opposing skip before counting starts (law 25).