Throw-In Violation - When to Call?

In the past week, I've had two situations occur which are similar to NFHS 9.2.2 Situation C. They occur as follows:

After a made basket by Team B, A1 grabs the ball and moves towards the end line as if to perform a throw-in. A1 never legally steps out of bounds before passing the ball to A2. A2 then begins to dribble up court.

Do I have an immediate violation or do I continue my 5-second count? Would there be a difference if in (A), Team A continues to play as if the ball was legally put in play and in (B), A1 yells to A2 to come back and throw the ball in?

In game 1, I continued my 5-second count. Game 2 had my partner blow the whistle immediately. Looking at the case book ruling for 9.2.2 (Sit. C), I would say that I was correct to continue the 5-second count. The exception would be if Team A makes a basket or Team B gains control prior to the 5-seconds elapsing, at which point I would call the violation even though 5 seconds had not elapsed. That being said, I won’t be surprised at all if you guys tell me I am way off base!

P.S. I'm new to the H.S. level of officiating, so I probably will have a bunch more questions for everyone.