Sorry to chime in so late in this thread after it has gone in a different direction, but I feel obliged to point out that "average pitching speed at age x" could be the least useful piece of information a player or parent could have.
Who cares what average is? Average doesn't advance to the next level.
As a practical matter, "average pitching speed" means a velocity insufficient to play at the next level, whether that next level is high school JV, MLB, or anywhere in between (with exceptions for a few pitchers with unusual command or stuff).
Why spend time nailing down a measure of failure?
A more useful measure would be an indication of where a player's velocity compares with the velocity usually needed to compete at the next and ultimate levels he's aiming for.
I think MidAtlanticDad had a similar idea in mind when he said these comparisons don't matter until recruiting begins.
As to when college recruiting begins, it begins for each player when he demonstrates there is a reasonable likelihood he will be able to help a college team win games. Could be 9th grade, could be 11th grade. Could be earlier, could be later. Could be never.
I was going to wait until I read the entire thread before posting. But Swamp nailed what I was going to post. Who cares about average? You know who the better pitchers are in your kid's age group. You know what the necessary numbers are to pitch at various levels of college ball. You can't control how good other pitchers are. You can only control your own situation.
Always work hard to become the best you can be. Make yourself visible in the right places at the right times. The right college programs will find you if you are where they are looking.