You did not say what motor it is but here are my suggestions.No there will not be any visible difference from rich to lean other than the a mount of smoke it will make when running.This is What I recommend you do. Open needle 4 turns counterclockwise ( very rich). While running carefully turn needle in clockwise, possible 1 turn. It should still be rich, not running smoothly. Do this with throttle fully open. You do not want to lean it out at this time. Continue doing this for several tank fulls but after first 2 tanks you can lean out from time to time but back to rich each time. Just do not overdo with leaning it. Depending on the engine it could be ready for flight sfter 3-4 times on bench but some may take far more to break in. Use 10% nitro fuel for this with 18 to 20% oil.
Be very careful the prop can do major damage to fingers.