Situation during Training

[flick23]

I recently passed the written exam and have been doing on-court training at a after-school program near me where they do scrimmages for 4th-7th graders (in other words, no pressure for us) and a board member from the local IAABO board critiques our mechanics. This is in preparation for the floor exam in the middle of December. I had this situation come up last night:

I'm the lead and call a shooting foul on B1, the ball goes in, score the goal. I go to the table to report ("score the goal...Blue 3-2...hit...1 shot", and my partner (who unfortunately is one of the less game-ready refs in training at this point) switches with me to administer the free throws. He gives the ball to the shooter before I am completely in place and counting ten seconds. I was a bit taken by surprise that he gave it to the shooter so quickly, but was pretty sure I heard him say "one shot". The shooter takes his shot, it bricks, and nobody on the line moves. My partner grabs the ball and goes to administer the second shot. At this point, I'm frozen, not exactly knowing what to do (this was only the second time I'd been on-court officiating).

In retrospect, am I correct in assuming that once I see him pick up the ball to administer the second free throw (incorrectly) I should have whistled and gone over to him to explain the situation and then the arrow should have been used to determine possession?