There are a number of important milestones in your kids' lives: the day they are born, their first word, the first time they sit up, then crawl, then walk etc. I like maybe the not so conventional (but I think equally important) ones like a good example would be the first time you try a Maxibon - life changing I tell you:)
(p.s. I only had my first one who I was 30 - thanks to Celeste for introducing me to these babies!).