Pretty much the same starting procedure as your 20-55cc engines. The only real difference is two cylinders and way bigger prop.
I agree I never flip a prop with ignition on above a fast idle I have a routine that works with my da 150 mvvs 116 gp 123 os 55 gp 61 mvvs 58
find a way that gives you a consistent result.. a well tuned engine needs to warm up a little to accept a quick throttle advance be sure to take the time to tune it
set on ground fly it and adjust from there as tune will change in the air