Hi!
I started teaching math after reading several threads in this forum. The following threads were especially helpful.
http://forum.brillkids.com/teaching-your-child-math/maths-equations/
http://forum.brillkids.com/general-discussion-b5/gentle-revolution-and-glenn-doman’s-method/
The answer to your question about turning off the words until step four is: Yes. You should just show the dots.
The book says you can do 2 sets of 5 cards as long as your baby is happy with that. Later, when you’ve taught the numbers 1-20, you’ll start adding 1 to 3 equations, 3 times a day. That means you’ll be doing 2 sets of 5 cards 3 times a day and 1 to 3 equations 3 times a day.
I found the dot cards at a consignment shop and was very happy.
It has helped in doing step 2. I’m looking forward to Little Math, as I hope that will make doing equations easier, too. Later, when your child gets to equations, Doman says you can start asking him questions like, “What is 13 + 6?” And show him two cards and let him choose, if he wants. If he doesn’t choose a card, you just show him the correct answer and say, “Here is 19. It is the right answer isn’t it?” (Very cheerfully) I don’t know what the Little Math program will be capable of, so I do not know if you would be able to do that without the cards. So, my long answer, to your short question is, “Yes, I think having the cards helps.”
I hope this helped a little. 
By the way, I just got to read the Teach Your Baby Math book, and I don’t think you have to buy it. If you have read the other books, it basically uses the same method to teach math. And the folks on this forum are very nice about answering questions, if you have more. But it was nice to read for myself, and he tells nice stories of other children and moms.
The following links have also helped me:
http://worldsbesteducation.org/math.aspx
http://worldsbesteducation.blogspot.com/search/label/Learn%20Math
The second link is Domanmom’s (the first may be, too?). She is part of this forum, too.