We used to start control line engines at full throttle since they didn't have a throttle, but usually RC engines are started at idle. It is usually easier and safer.

When your car starts from cold, it has a fast idle setting built in that keeps it reved up until it warms. I start RC engines in a like manner, at a fast idle and let them warm up.

I choke or prime, then close the throttle and run the throttle trim to full up. I you have an all digital trim radio, open the throttle about an eighth or slightly above your normal idle setting. The engine should start easily at this setting. I leave the battery connected and let the engine warm up for 30 seconds or so. Then I advance the throttle to blow out any residual prime, reduce to idle, lower the throttle trim, remove the battery and go fly.