Panel 1: We set up the punchline not only by having April wear a dark-coloured onesie but also by having Elly compare the year April's been alive to the blink of an eye.
Panel 2: This is because Elly once again forgets that children move even when Mommy doesn't will it so. This means that Elly's boasting to Connie about how April is into eighteen-month outfits, toddler toys and a full-sized crib will be followed by her being into something Elly doesn't want her to be into.
Panel 3: Since Liz has no initiative and can't stop disasters but merely report them, she yells that April is into the flour bin. At least she ain't into the bleach, detergent or weed killer.
Panel 4: When John comes to see what the fuss is and asks what happened, bleary-eyed idiot Elly moans that she blinked.
Summary: Since this is a strip written by and for angry idiot women who think that adapting to the kid means the kid is a monster who wants to enslave a mother she hates, it's April's fault that Elly has her head up her arse.