I picked it up somewhere on this forum a couple months ago and only tried it back then not very seriously.
But oh boy, am I hooked now....
Kudos to the person who came up with this.
Set # lasers to 0
Place your ice harvesters in the bottom two low slots (and lock mods again

Tell TM(+) to turn on those two low slots (like it where shieldmods) as soon as the ship undocks
Alternative is that you place them in your med slots, but because I have two civil shield boosters there and I don't want to have a horizontal, but rather vertical setup, I use the low slots.
What happens is that TM will turn on all the pre-chosen med and low slots. This will turn on your shields as soon as you undock, but also will it make your iceharvesters active to start on the first lock they get.
Your mack will then warp to icebelt and TM(+) will always lock one iceroid, always... thus making the ice harvesters active without delay.
I tuned locktime to 2 seconds less, I turned down mining time from 818 sec to 805 and I turned down warptime just a little.
Per run this will save 20-22 secs for me. Every 40 runs you will get one run free this way adding another 24 cubes to your inventory.
It's actually a 3% extra profit

About 'warp to' time. I used to be in a system where I was 90 seconds away from belt. Now I am for convenience in a system 70 seconds away from belt. But I used to have it on 53 seconds when sitting in another system in a station closest to belt. That is a huge timesaver, never forget to take those kinda tricks into consideration. If anyone knows without saying the name, systems with even lower distances, then shout and I go scouting again.
