It really does come in spurts.
Back at the beginning of Summer, Joshua's 2T pants were too short but we couldn't find any pants since all the stores only carried shorts. We got our first couple 3T pants from Nana just as soon as Target put out the fall line. Since then, I've bought several more pairs of 3T pants and packed the 2Ts away. For awhile I was rolling the cuffs. And then, all of a sudden, those 3T pants are high-waters. Looks like I'll be buying a second set of pants in one season.