If your DD wants to do it, then I don't see why not. I think there is a whole world of difference between those children who want to do it, and those whose parents want them to do it!
My DD started looking at letters at 2/3 years old. So we got her the jolly phonics books. We only got the ones that you look at the letters and we put them on the bookshelves and let her bring them to us. When she wanted to do them, we would spot the sounds in the pictures, and then spot the sounds around and do the actions. Nothing more than that really.
From there, she easily took the next step to working out CVC words, and then reading was an easy jump. She is now in Reception, and has fab reading skills - she's reading year 1 books at school, and they're working hard to ensure that she doesn't get bored (so that is not necessarily a problem). For example, other children are learning to read, she's learning to spell and at home, she's just starting to read Enid Blyton books (but needs some help with the old fashioned words).
However, she finds learning to read easy and fun. She has driven this, not us and as I started off saying there is a big difference between a child who wants to do this, and the parents who want their child to do this.
Apparently children usually learn to read anytime between 3 and 7.
HTH