Some research says that six-month-olds are not ready for books, which I personally disagree with.
I haven't had the luxury of doing an enormous study but I did read to Cedar practically from birth and by a year and a half he'd sit and look at books on his own. Now have a six-year-old who really loves story time. So I'm going with the earlier you start the better.
However, there's a difference between reading to your baby and making reading time fit your baby.
For instance, while your little one is still into eating rather than reading make sure you offer her books she can safely nibble. There are plenty of baby-proof, rip-free, fabric and soft plastic books out there. She can see words but not seriously harm the book.
Look at the book; don't simply read. It's okay to flip through a book and just talk about it with your baby or toddler. Ask questions about the pictures or place your finger on a picture or word and say it.
Grab a good mix. I've never limited the books I've read to Cedar by reading level. If he picks out a book "meant" for three- or nine-year-olds I don't argue. He loves books for many age groups and is even starting to like books with few pictures like Where the Sidewalk Ends.
Don't say no to repeats. Your baby and soon-to-be toddler will fall in love with certain books and you should read them over and over if that's what she wants. The first word Cedar ever recognized and pointed out on his own was a hard word. It was "Harold" which is likely due to the fact that he's made me read Harold and the Purple Crayon about 1,345 times.
Keep books within easy reach but make book rules. I'm pretty chill and we don't have all that many rules at my house. But since Cedar was a baby, I have stressed that he doesn't hurt books EVER. You don't color in them, rip them, step on them, etc. I have always kept his library of books where he can reach them and he's never hurt one yet. If you make books important, your baby will realize from the start that they are.
Don't just read at bedtime. Read as often as possible and give books, not toys, as some of your baby's birthday and holiday gifts.