I started reading books as soon as I learned the alphabet, I was 4 years old. The first book I read was a story from Panchantantra (a Hindu book of fables). I did not read for the story, I read the book because I was happy to see the words I had learned.
I've always been fascinated with words, spelling, reading. So I'd say as soon as I learned to read is when I started reading as a habit. There's just something about being lost in books. Learning something new.
I was around 5 years old when I first started reading and it was my mum and my grandma that got me into reading. They would buy me books randomly or they would buy me books for my birthday or Christmas and I would love reading them when I had the time.
I feel like I picked up the desire to write (since I was like 7-8) before I picked up the interest to read, but that they both came a little hand-in-hand. I needed to know how to do it, after all.