hi. here is how i did it, although i had a pretty good cooked diet before i started going raw.
start with one meal a day, ideally breakfast. change breakfast to a really mellow green smoothie, say one with fruit you like and romaine lettuce. have as much green smoothie as you want for breakfast. or just eat one kind of fruit until full, for breakfast.
(if you go for a lot of fruit and its not through a straw, brush your teeth afterwards.)
eat the other two meals as you normally would until you really feel adjusted to that one small change. monitor your baby. see that he is adjusted too.
then start doing a raw lunch or dinner too. you can choose which. it might be better to go "raw till dinner," for this transition, although i feel that in the long run lunch is the better big meal.
i would change lunch, when you are ready, to a hearty raw meal. think seeds more than nuts. there are so many hearty recipes.
then eat your usual dinner.
only when that is really adjusted would i go all raw.
this is a great time to get nutrition into your child. as well as to already show your child that you take good care of yourself. (this of course, is the best way to get him to do the same for himself. )also, you will be able to start him on raw when he eats solids. THAT is what will help him really clean up from any bad eating you had going on before, and even any mild detoxing that he goes through with you.
babies show things quick. if he shows detox symptoms, back off for a few days. but go to something still nourishing and organic. make sure all your desserts are raw. and relax, this is a treasure trove of pleasure not a restriction.
even when you are all raw, eat a lot of fats. you can still lose weight -- see alyssa cohen -- a nursing mother needs fats.
there is such a range of raw--you are not going to juice fast while you are nursing, but getting raw nutrition in you is going to make this time even more magical.
:)