I've always thought to simply start the timer when you start the pump, and then note when preinfusion ends. Exactly like the post above, except I am just doing it in my head because I am using both hands to pull my shot with the lever.

If you take notes you want to likely get as detailed as your machine let's you - I have a lever so I note my pressure profile along with the timing.

Jeff wrote:For a typical E61 box or SB, "18 g in, 36 g out, in 25 seconds from pump on" seems to be a reasonable benchmark. There's nothing magical about those numbers. Your tastes, coffee, and gear may eventually settle on "17 g in, 42 g out, in 30 seconds" or whatever. The idea is that you get from "blech" to your "generally good" benchmark quickly, then can easily tweak to "great".

This.

Lap times?? Brilliant! I gotta try this.