I say no. I could read - and I mean read - age two without this (pre-school, age 4, I was reading short books of fairy stories - and I don't mean memorising them). DS is exposed to more "how to read" stuff than I was (I just had books) and he is only just starting to get interested in reading.

If your child WANTS to read, your child will read. When your child is ready. And there is nothing wrong with that at all. Flashcards - well. Useful revision aids, flash up a word and define it to the exam spec. For teaching? No. Not at age 16, not at age 6, not at 6 months. You don't learn from flashcards, unless superficial recognition and a fear of getting things wrong is what you aim to teach.