C.S.
I didn't send mine until they were 4 for half days but they also were out of the house at day care, private, 3 days a week while I am at work. If you want something to stimulate him maybe do a evening or weekend class at the Y or a music class. Makin Music has great classes I did them with both of mine starting at 18 months. The classes are 1 a week for 45 minutes.
Ref work,sah...dont' let others make you feel guilty. Do what is right for you, your child and husband. No one knows you better than you, financially, mentally etc. SAHM, working moms, etc..each brings something different to the table. You don't have to be a SAHM to be a good Mom. I work part timea nd I don't think I'm short chaning my children..I think it's good for all of us.
Take care and keep your chin up.