Probably a sneak attack is best.
From 2013 after we adopted Boo, we kept him in isolation for a couple of weeks to let him build up his confidence and give the other pets time to adjust. The night before letting him into the house for the first time we let the other pets come into his room. Boo was eager to impress his older brother. Fortunately he did not follow through on his instinct to jump on Sam from behind.