I read to myself while nursing (only thing that kept me awake for the 1.5 job in the middle of the night - avg 45min nursing, 45 min burping). I'd sometimes read out loud, but more often read silently.
Probably right around a year I started reciting poetry to him before bed (Eugene Fields, mostly, and some Kipling, and a lot of 'anonymous')... the rhythm helped him fall asleep. Also somewhere in between 1yo & 18mo we started heading over to Barnes & Nobel (giant bookstore) a couple times a week. He'd play with the Thomas the Tank Engine set and we'd look for books to buy (meaning *I* looked for kid's books that didn't bore me). More often than not, we didn't get a kid's book, but I got an adult book*
I BEST piece of advice I ever got with reading to kids is to read books YOU like. You liking them translates in 100 different ways nonverbally, ditto if you're bored/ don't like them/ think THEY should like them. The best way to keep a child's interest is to actually be interested in something yourself. This meant our book list was actually pretty short, as most kids' books (imo) are pretty terrible. There are some *great* ones out there, but there's also just a lot of garbage.
* I didn't read to kiddo regularly. I myself, however, read voraciously. So I just waited for him to ask. From our rainy day bookstore jaunts we had probably about 20-30 kids' books on the shelves/floor. When I was bored, I'd occasionally bring one out... and as soon as he started wanting to chew on it (board book) I'd hand it to him and start reading my own book. Then he started copying me. Gradually it shifted to HIM bringing out books and we'd read and read and read. I'd mess up the words from time to time to have him laugh and correct me. I'd always trace the line of words with my fingers.
By 2ish, without trying at all kiddo knew all of his letters. (Of course, some of the books were alphabet books... like Dr Seuss's ABCs... Aunt Annies Aligator! A, a, a! to Zizzer Zazzer Zuzz... why I am! - I haven't read these books in at least 4 years, pick your books wisely, you'll memorize them by heart). We also stumbled across www.starfall.com at right around age 2. HUZZAH! (I have an adhd-c kiddo, didn't know it at the time, of course... but that was my only hour of peace all day, him playing with his letters and words on starfall while I did the dishes, took a shower, etc.). The downside is that he was reading simple things by 2.5, and reading fluently by 3. ((The downsides of a reading toddler are enormous, but I won't go into them now)).
I actually read a LOT more to kiddo once he was fluent in reading than before he was fluent in it. I'm adhd-c myself, and get caught up in things. So when I'm reading out loud I do the voices I hear in my head. Kiddo LOVED silly voice books... so we did a lot of kid's books that leaned toward expressive reading. We'd often "test" how good a book was at the store by sitting and reading it out loud. If you get very wrapped up in the story you can end up with a whole garden of children at your feet the next time you look up. <grinning> Which is fun.
ANYHOW... never too young to start, but keep in mind that kid's learn far more from modeling then telling... and that they *pick up* on your frustrations (aka don't make it a chore), and your boredom (choose wisely).
*** PS ***
My son DROPPED reading like a ROCK at age 4. He'd found numbers, and moved on. He still has apx the same reading level now at age 8, as he did at age 4. Kids DO go through phases. I thought I had a bibliophile on my hands and was dead wrong. He loves stories, sure. But not reading. Reading he can do, but doesn't really enjoy it. Math, science, movies/filming he loooooooooves... but while he's very competent at reading, it's just not his schtick. As a writer, I've had to really check my ego on that one.