When did my baby grow up?!

I know I've probably been saying this for months, but when did my little baby become a fully-fledged, walking, talking, on-the-cusp-of-reading toddler?!! I can't believe how she's suddenly copying nearly every word we say, and remembering them later. On top of that, she's understanding far more than I thought any 20-month-old could. Since Christmas I've started a project with her on houses, and am working in an exercise book with her entitled "Where do I live?". I've put in photos of her house, her uncle's house that we visited in December, and her grandparents' house that we visited just after Christmas, and she loves looking through it, talking about it. I also put a small map of the country in, with an arrow pointing to the area where we live, saying "I live in [town]". Today she handed me the book to read to her again, so I started by reading the title "Where do I live?". She immediately answered with a word that sounded very like the name of our town! I thought I must be imagining the similarity, so I checked by reading her the page that said "I live in [town]", and she again repeated the name of the town, exactly like before. So suddenly, she doesn't just understand the question "Where do you live?", but even knows the right answer - amazing!