skylark - Nope. I copied all the settings provided by @DavecUK in his review as part of the advanced settings. For both Steam and Boom pre-infusions, I set the time to be 10s. I am for 18g in, 36g out, over 35 seconds, approximate total time.
A bit more, a bit less, I’m not going to stress over it.
So you are going to ask me… “But, when do you actually stop the shot?” When I reach the desired output. If the timing is off, I adjust the grinding accordingly. Do I care if it’s 3 seconds off (plus or minus)? No.
:-)
Also, to hit a more consistent timing, make sure you flush the machine until water comes out of the group. Sometimes it takes approx. 2s for water to show up - which can make a difference in the initial pressure specially when using bloom pre-infusion.
Hope that helps.