I haven't worried too much about our kids being "ahead" or "behind" in terms of various milestones. It's still way too early for any justified hand-wringing, better instead to invest that energy towards helping our kids have happy childhoods. It helps, of course, that they generally seem cognitively bright and physically healthy.
Still, I'm ever the documentarian. So here are some notes on Jada, circa age two and about four months (Aaron's still too young to even think about milestones). Note that some of these are relative to other kids we know from church and park, and some are to what the pediatricians say in the books.
* Ahead - She knows six colors, plus all her letters and numbers, and can count to ten.
* Regular - Her vocabulary and her climbing abilities are on par with that of other kids her age.
* Behind - She doesn't speak in sentences except for very simple ones, and isn't anywhere near being potty trained.