I find it intriguing that there would be no agreement on how to time shots. I guess really there are two things that people get caught up with in this discussion:

1- The timing of extraction

2- The timing of a shot

Among professional circles, Barista trainers, and companies that run espresso classes and what not, there is not dispute about this whatsoever. I only ever see divergence among home Baristas (and I am not knocking HBs, I have found that they have been a major driving force in the advancement of professional Barista techniques). Because of the variations in different types of pre-infusions (or lack thereof) in different machines there is simply no way of consistently knowing when different definitions of extraction begins. The only bench mark that one can go by is the switch. Start your timer when you mash the button.

It is a fact that the pregnant pause as we wait for that first drop is going to be dependent on many factors. The magic number will be for that coffee, with that grinder, on that machine, on that day, with that many people crowding close and breathing on the coffee. The numbers only serve the greater purpose of taste profile anyway, so it is not that big of deal after a Barista, Home or Cafe, is in the Zone.

I keep teaching the importance of the numbers as guide lines to espresso students, and then I drive it home to them not to get so stuck on the numbers. I like to ask a new Barista

"why did you stop the extraction at that point?".

The are usually only one of three answers,

"because the timer says 25 seconds" or "because the shot glass was at 2 oz", or "because it looked like it was about to go yellow". I try to keep a pack of gold star stickers for the best answers.

Peaberry wrote:I find it intriguing that there would be no agreement on how to time shots.

Discussed elsewhere as well, the 'Golden Rule' of 2 oz in 30 seconds is filed under the 'How to get this thing off the ground' instruction. Most agree that it starts when the switch closes, but I'm not sure how that applies to pre-infusion, much less a lever machine...
There are hundreds of thousands of combinations of; machines, tastes, tampers, techniques, personalities, coffee blends, water types, elevation/intrinsic atmospheric pressures, ambient temperatures, humidities, and phases of the moon.
Each of these (arguably) will affect the outcome of any given pull. To suggest that any one person will have the answer for your (insert list of variables here) in an easy-to-remember cliche adage posted on the internet is hopeful, at best.
What we tend to do here is to post our experiences and empirical anecdotes for you to sift through and decide which apply (either through your own identification with any given poster, or your own empirical experimentation) to your particular (insert list of variables again here).

No one here is any great source of accurate information on your kit at your house with your water, coffee, grinder, tamper, etc.
Ask the questions, gather all the answers, sift for relevance.

Psyd wrote:Ask the questions, gather all the answers, sift for relevance.

I tend to agree with Adrian (drdna). Extraction begins when the espresso begins to extract from the puck with the first drops. This can take into account pre-infusion, dose, grind. and other variables. Brewing begins with the flip of the switch i.e. when you start the brewing cycle. Sounds good to me. Do you agree?

I can live with either definition (flip of the switch, appearance of the first drops). Consistency of shot timings however you measure and stopping the extraction by color are more useful than stopwatches. I cannot remember the last time I timed a pour.

Here's a system that will serve.

The "shot time" is from the moment the pump starts to when it stops.
The "dwell time" is from the moment the pump starts to the moment you see the first drop.

The absolute timing on either is quite flexible; but no matter what the machine, a dwell time under about 4 seconds or over about 10 is trouble, and a shot time of under 20 seconds or over 40 is trouble.

The most important thing is consistency. Once the shot is dialed in, you should get the same dwell time, same shot time, same volume and same level of blonding each time.

If you are a raw beginner, you will have more luck doing a strict drill of 27 second, 1.75 fluid ounce shots than going by blonding, zen, instinct or anything like that. This is because all those require some experience, which you'll only get by first following the drill.

another_jim wrote:Here's a system that will serve.

The "shot time" is from the moment the pump starts to when it stops.
The "dwell time" is from the moment the pump starts to the moment you see the first drop.

We should adopt this nomenclature. It eliminates ambiguity and makes perfect sense. Thanks Jim!