You will not be able to adjust or check your idle . Idle speed and mixture need to be adjusted at operating temps. You will not be getting to operating temps on the ground, or at least you shouldnt.
This is important to remember on your first flight. Your idle may be too high, causing float, so make sure you are on a suitable length runway. Your idle may also be too low and can cause engine stoppage on landing roll out.
Not a significant event as long as you plan for them. (I just witnessed the later on an RV-10 first flight. Long time test pilot anticipated this during his test flight and landed in a direction on the runway so he could coast to parking rather than have to stop or turn around and have to restart the engine.)
The most important thing as mentioned is to insure that your oil system is primed. You should see oil pressure within 30 seconds or sooner.
The first engine start is really a verification that things are wired and plumbed properly and that you do not have any oil or fuel leaks.
Make sure you have a buddy standing by to alert you to shut down if there is any sign of fuel or oil leaking. He can also man the fire extinguisher.
Check, double check, your brakes, or better yet, tie the tail down. A first engine start on a twin that had the throttle wired backward on one engine recently resulted in a pirouette and a wing tip into the neighbors hangar. Not pretty. Same thing could happen if one brake failed.
Make it short, be safe, and have fun.
Smart People do Stupid things all the time. I know, I've seen me do'em.
RV6 - Builder/Flying
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.