I use the ULTRACHRON timer on my Samsung (free version). I never change the way I do timings. I start when I get in line and hit lap each time something happens. Another register is opened, I hit lap. I reach the counter, I hit lap. I finish ordering, I hit lap. I receive my order, I hit lap.
This way regardless of the MSC and what they want, I have the timings for every scenario. I even can add EXTRA detail like (additional register being opened after a specific amount of time).
I know certain shops don't ask how long you waited in line, but if I do the timing the same way every time, I don't have to worry about which shop I am on and what way they want it done. I have ALL the data and use the info they need.