James, if you are going 3-4 mph and want to shift into first without stopping, you would only have to slightly increase the revs to match your road speed and it would drop right in to first.(do this with the clutch pedal out, by feel)
On a synchromesh transmission, in my experience, double clutching is unnecessary. It's usually only needed in non-syncro transmissions.
I know with a very heavy vehicle and only 3 gears, I would always use first to get the old girl moving from a stop. On some 4 and 5 speeds you can skip first but not many 3 speeds are happy with that.
Good luck on the quest for a working combo, James