The recommendation I got given for the Twin Comm was if cold, prime until fuel flow indicated, then wait for 3 seconds, then ICO & crank.
If warm, "prime" till fuel flow indicated, normally very short period, which made sure that the lines were full of fuel rather than vapour, then ICO & crank.
In both cases, the throttles were "cracked" open less than 1/4". Over the period I had the aircraft, it always worked, regardless of how cold, or hot, the engines were.