Recently I started reading to my 4-month-old a lot more of my older boy's old board books. Little bro seems to be more interested in them now. I point to words and often check to see if he is looking in the direction of my finger. He often is! (If he is looking away, I stop reading--it means he's done.) Around this age, babies are able to discriminate smaller objects. For example, see:
http://www.babycentre.co.uk/baby/development/05mth/#10 If you limit yourself to large-sized print when showing something to your baby, you are probably greatly reducing the total amount of print your baby is exposed to. I'm sure that using large cards with nothing but a word or two on them makes it much easier for the baby to see the words, and that's great as far as it goes, but if you can read a lot
more, which IMHO everybody should, then by golly, it's time to use regular baby books. Don't underestimate the amount that a baby can pick up from such books. I'm sure that my older boy learned a boatload about language from my copious early reading. I think this is what made it so easy to pick up reading when I started teaching him to read, "late," at age 22 months. If we had limited ourselves to the few (commercial) flashcards we had before that, and didn't do much book reading, I'm sure he wouldn't have learned as fast.
Of course, you might argue that if you use LR or other electronic flashcards, the supply is almost endless. Maybe...but you're still cutting your child off from a lot more enjoyable reading experiences, if you don't read books so much. My boy
loved Curious George, for example. Besides, you're not really following the program if you read so many flashcards to your kid. But there's no upper limit--just what your child wants--on the amount of time you can spend reading to a child.
BTW, we use the iPad a
lot these days for flashcard-type experiences. Text is big enough, and I can put it close-ish to his face. (Just don't drop the iPad on the baby!)