A.H.
You might want to figure up what it would cost you to work and put your son in daycare (don't forget to include the costs of "extras" like work clothes if you need them, and "convenience" foods if you don't have time to cook due to working, etc.) vs. how much you would spend hiring someone to do your job while you stay at home with your son (this is how I became a SAHM). Definitely count your feelings and your husband's feelings as important, too! Then figure out which option is most worth it to you and your husband.
If you decide on daycare, make sure you feel comfortable with your son's caregiver(s) before leaving him for a full day. If you're going to be worried about him, or constantly checking up on him, will you be able to do your job effectively? Will daycare be too stressful for you, or would the financial cost of hiring someone be more stressful?
If you decide to stay at home, are there parts of your job you could still do from home (scheduling clients, for instance)? Could you hire someone part-time, or even take your son with you to work (not possible for most of us, but if you own your own business, it might be an option)? Are there concerns you may have about staying at home that need to be addressed (boredom, need for social outlets or intellectual pursuits, etc.--these were never an issue for me, but for some, they are)?
Just some things to think about, since ultimately, you're the only one who knows what would be best for you and your family. :-)
--A.