Arvi,
Glenn Doman in his book " How to teach your baby to read" states that once a child has acquired a basic reading vocabulary of single words he is now ready to put those words together to make couplets. He doesn't really specify how many words baby needs to know. Although he describes areas of words you should present first to a baby:
Objects, Possessions, Foods, Animals, Actions. In each area he gave an example of 12 single words that gives total of 60 words.
So when you want to present couplets example: orange juice, baby should know these words already. If you presented enough single words to create couplets go ahead and don't wait. Introduce colors and create new couplets.
Baby will be happy seeing old words he already knows that can create a new idea. Beside that you still will be introducing new words by reading books to a baby.
There is no wrong way for teaching baby how to read until you do this without enthusiasm and joy!
I wrote a first post on my blog about my way of teaching reading
http://earlylearning-eaton.blogspot.com/. It's not perfect Doman method though, but you can find some ideas about books you can create for your baby in near future.
If you want to do this perfectly as Doman says, it's always good to go back and re-read "How to teach your baby to read".
I hope that helped a little bit.
Enjoy your teaching!! The result will be astonishing :-)