MHO is that at 3 1/2, he should still be learning everything through play. (There might be an exception if he's a true genious, but then he'd probably be reading already and/or spouting math facts that make your jaw drop.
) He's obviously a bright child. I have one myself, and I understand the temptation to run with it. It's possible that he *could* sit down and start to learn to read and write and do formal math. But *should* he? I believe (have only heard, not seen for myself) that studies show that children who learn such things early are generally no more advanced than those who learn later at their own pace. The later learners catch up fairly quickly once they get going.
Another thing to think about: if you sit down and teach your son to read, you may miss out on the wonder of seeing him teach
himself to read! My dd was showing most of the signs your ds is showing at 3 1/2. At 4 1/2, she began reading on her own. In the mean time, I answered her questions about words and letters, and she learned some stuff from educational tv shows and computer games. But I never sat down with the intention of teaching her to read. The process was very organic -- it all came from her. It was truely a wonderful process to behold, and I would hate to have missed it because *I* decided when she was ready to move to the next step, rather then letting *her* initiate each step, kwim?
We did start a formal math program when she was 4.25. Do I think I started too soon? Not necessarily -- I'm not an unschooler when it comes to math.
But I'm glad I didn't start earlier, and I don't think it would have hurt to wait. While she could grasp most of the concepts, I could see where her young age limited her ability to fully understand some things. After a few months, she gave up math lessons in favor of all reading all the time. :LOL Besides the diversion of books, I think we had reached a place where she was hitting the upper level of her ability to comprehend. Only age and maturity would allow her to go further, so we took a break. In addition, it was hard for her to focus sometimes, even when she
wanted to do the lessons. I would suggest stopping, and she would say "no", but then she couldn't/wouldn't pay attention to what we were doing. It got pretty frustrating sometimes. Again, it's a maturity thing. I plan to start up with the lessons again in the fall or later this summer. She knows some children going to Kindergarten and is eager to "do" some Kindergarten homeschooling.
Since math is my only curriculum, I hope it does the trick for her! :LOL
So my advice is to sit back and watch him for a while. Just observe him and see if you still think he needs more than what he's already getting through play and interaction with you and dh. If he seems bored or is asking for specific instruction, then you can start the kindergarten materials. If he seems to be learning and growing and happy without them, then I'd hold off for a little while. Just my 2 pennies!