I'm ordering some summer clothes online for LO who is 4 months. So far he's only ever worn sleepers and onesies with pants. I see a bunch of cute t-shirts (i.e. not onesies/bodysuits) and also non-footie separate PJ's... wondering when you started dressing LO's in separates? Is there a certain point when onesies or footie pajamas don't work well anymore?

ETA: Follow-up question... sizes seem to jump from 0-3, 3-6, to 6-12 (i.e. from 3 month spans, to 6 month spans). Is that because they grow at a slower rate during those 6 months? Can't imagine him fitting in the same clothes for that long, right now it feels like he's a new size every few weeks!