She still wears a pullup to bed, but it's usually still dry come morning.
I wish I could point to something special we did to make it happen so we can do it with the boy, but one day, instead of her usual "no" in response to "do you want to go on the potty?" she just said yes. Ever since, she has been great at telling us when she needs to go.
We did do the potty dances and celebrations, which she now does for me on occasion. We also offered M & Ms after her first pee and poop on the potty. But other than four minor "accidents" early on in the big girl panties, she's since been accident-free.
Meantime, the four month old is now wearing the same size diapers his sister just finished with last week. He's up to 17.5 lbs and is wearing 6-9 month clothes comfortably. I find myself Google and Binging "pituitary giant symptoms" and other worst-case scenarios, but thankfully, all appears to be well: he's just a chunky boy with delicious little rolls to kiss and clean. Except for that milk- and lint-capturing neck fold: NAS-ty if it's missed over a couple days.
They both are just growing fast. We're looking forward to hearing the first syllables out of the youngest. He hears a torrent of words each day between the rest of us, so he should not lack for inspiration or vocab. His sister's latest addition is "Look at my illustration." We're looking little one. We're looking.