I have a Yanmar 1GM in my Ericson 26 with just under 1500 hours on it and here's what I find works best:
I set the throttle to full and push the start button. It always fires almost instantly (usually in 1 second but always within 2 seconds max). I then immediately throttle it back to the throttle position where it "clicks" into place just forward of neutral. That is, it's not neutral (straight up and down) but where the throttle clicks in about the 1:00 position. Then after a few seconds, as the idle speeds up a little, I might throttle it back just a tad to the desired idle speed. It's important to throttle it back right away, obviously, because you don't want to race the engine at full throttle while you are first starting it up.
I have several different Yanmar manuals for the GM series and there are a few different variations on the starting procedure. But this is the one that works the best in practical life for me. My engine, by the way, appears to be in good running order and it always starts instantly with this setting--even faster than my car!