Small Breakthrough

This past weekend, I only had one game scheduled. That's a little frustrating, as my learning curve has been slower than expected. I guess I can't complain too much though. My game this weekend was a U-18 state cup match.
The breakthrough in the title refers to my confidence level for this game. I was an AR, but I somehow felt like I actually knew what I was doing. My signals to the center referee were confident. I learned to pause for a second before signaling. All in all, I felt I did really well. This could be a result of lessons learned from my other games, my study of refereeing through books and websites, or, most probably, a combination of those things.
Every time I have a game, there is a lesson to learn. This game was no different. In this case, the lesson related to flagging offside infractions. I had a situation where an attacker, on the far side of the field, was in an offside position by several yards. Her teammate played a ball through the defense, straight toward the goalkeeper. My reaction was to wait to see what happens before putting up the flag. The offside positioned player had not yet touched the ball, and the ball was playable by the goalkeeper. The striker did get to the ball and I immediately flagged the infraction. The center referee spoke to me later and asked that I flag offside earlier. His take was as soon as the striker made a play for the ball, the stroke became involved in active play and the flag should be raised. I asked my instructor and he agreed. He did say that, in the event another striker, coming from an onside position, was making a play for the ball, the correct action is to hold the flag to see who gets to the ball first.