I seem to get an initial flow of espresso during pre-infusion. Specifically the espresso beads evenly (but quickly) on the bottom of my PF and then flows for about 5 or 6 seconds (about 5g of liquid) until my pre-infusion kicks in. Then it stops during the balance of the pre-infusion and then continues.
I have a Lelit E and am using a 15g IMS basket with a fairly thick metal puck screen. I typically fill the basket with 15g of coffee. I suspect that this initial flow occurs when the Lelit is filling the group. Perhaps there is just not enough headroom in the basket due to the screen. But I like the distribution evenness that the screen produces.
Is this a good or bad thing? What should I change?