Instead elbows are bent and extend after contact. My question is at what point?
The arms should naturally extend immediately after contact. The location of the arms in space once they extend will vary depending on pitch location. For a right handed hitter I would say that on a pitch down the middle the arms will be pointed over the pitcher's head, on an inside pitch they will be pointed to the left side of the pitcher, and on an outside pitch they will be pointed to the right side of the pitcher. However you would never teach this.
What you teach is the concept of extending the arms through/after contact. Or as Tom says the proper sequence.