If I had to do it over again...I would start the habit training like other's mentioned, start a home library now and read, read, read all the good books you can get your hands on, take him/her to the library for their activities, park days all the time (outdoor time), trips to the zoo, puzzles, play-dough days, painting, museums (hands-on for little one's), limit noisy toys and twaddly books (gifts from inlaws, etc.). I can think of more if you like, but I will stop there.
If I were you...I would start reading CM material now, weed out of your mind (by asking questions) those things that are not necessary for a home education and save yourself some $$$ and time, get a binder (Planning Your CM Education might be premature, but I don't know) to jot down ideas such as books, activities, curriculum (familiarize yourself with the material and know what you would/would not use), prices, etc. I believe after looking at things yourself and knowing your own personality you can become a good judge of what would and would not work for you.
I hope that helps and does not confuse:)
Oh, one more thing. Have fun and let him have fun, too!
