It only kicks in if the food she is desiring at the moment is not available. She was perfectly fine at the Wedding with that giant cake sitting right in front of her the whole time, and she was anticipating eating it. It's wasn't until the cake was destroyed and she couldn't have it, that her hunger pangs kicked in.
Same thing with the croquembouche. She wanted it, but there was none, and thus her hunger pangs kicked in. On Wano, the only food she was desiring was Oshiruko, and she got to eat it.