Not sure I understand what you are trying to achieve Paolo "waiting to heat up". Do you mean from stone cold? Or, having pulled a few shots, waiting to heat up for the next one?
Your 0.9 bar giving 93-95 is a good setting, though I find 95 a tad on the hot side.
My view is that you should set and forget the pressurestat once you have achieved your desired temperature.
You can experiment with more or less boiler water level so that more or less of the heat exchangers are immersed.
But again, Id fill to the manufacturers recommended level, set the pressurestat, and do the temperature tweaking by coolish flushes only.