Welcome Heidi,
So very glad you could join us!
I would first spend some time observing the possible teacher and classrooms that DS would join. I love the idea of starting PT. I guess that it certianly might not work, but this is one of those times when I would encourage you to try it on the basis that it would help so many others if it works. In fact I might consider having a little talk with DS and see if he wants to be a pioneer and trailblazer for other gifted kids who are going through what he went through. That gives him an out if things do go bad, which is both good AND bad, so think carefully first.
Let's face it, I doubt that he is going to get Chemistry before Middle School and I'm guessing that he is already past Middle School level chemistry. (I'm thinking he might be ready for 'The Teaching Company' Programs on chemistry - maybe the school will buy some for him to watch? Or your local public library?) I'd also check 'Spark Notes' on Chemistry - as they have a 'simple, direct' approach that is more business-like than a High School text book. Much more white space on their pages. Loads of facts.
Anyway - so glad you had the good sense to pull him from the kindy situation - how sad!
Smiles,
Grinity