Do you start timing your shots when you turn on the switch or when the espresso first comes out of the portafilter?

Is this a 28 second shot or a 38 second shot?
Thanks!
Jeremy

When the water makes contact with the coffee, i.e., when I push the pump on switch. For more previous discussions, try some of the site's forum search tips. For example:

• When do you start to time the shot?
• When is the start of extraction time?
• Timing of extraction starts when?
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• Pour time begins when...

The majority agree the timing starts when the water first makes contact with the coffee, i.e., when the pump starts.

Q: When do you start timing your shots?
A: When the cup hits my lips..

I quit clock watching a long time ago.

Randy has a good point. I do time my shots, and I start the timer when I turn on the pump, but it's really only just to give me a frame of reference for repeatability if I happen to stumble into godshot territory. I will drink any shot that I pull that takes longer than 19 seconds and less than, say, 1:10, although in my opinion even the way-too-slow shots are worth tasting as long as your boiler temp is set not to burn anything and the volume of the shot is at least around 1oz. To me the only "sink shot" is a superfast gusher.