I work on the assumption that the piston crown is going to heat up much faster than the cylinder so I let it run at just above idle to keep the internal heat down and hold the cylinder until it becomes uncomfortably hot. Then I'll go to about half throttle for a few seconds then ease up to full throttle. However with my CL ABC engines I start them from dead cold at full throttle (that's all they've got ) and say what the heck, there's nothing I can do about that and go fly