The four stages, from newborn to adult
Stage one is what I call the larva stage: from birth to about three weeks. They get cuter and cuter as they go. Stage two is the super cute puppy stage, from about four to sixteen weeks. They get their wrinkles and finally turn into what we call a bulldog. They're like toddlers: walking, and you start seeing their personality and their structure. This is where you really bond.
Stage three is the lanky teenager stage, the second longest: from about four months to about 18 months, possibly two years. They get better every day, but it's my least favorite stage: you know they're going to be pretty, but they're going through their awkward phase.
Stage four is the adult stage, where you finally get what you've been waiting for: the head develops, the thickness develops, the functionality. They're normally fully developed between 18 and 24 months. All of these are give or take, depending on the line.