A few times now, I have gotten Fleur to sleep right after eating lunch. I know the daycare times it this way. It seemed arbitrary until I tried it and found it easy to get her to sleep.
Then I remembered something I read a while ago: Meats contain tryptophan. Fruits and sweets contain carbohydrates. At Thanksgiving and Christmas, we eat feel drowsy because of eating both. The carbohydrates prompts the release of insulin to use the branched-chain amino acids in rebuilding muscle, but the tryptophan is left behind. The tryptophan is metabolized into serotonin which is metabolized into melatonin. The last is what gives us that drowsy feel.
So, I now suspect the trick to getting the little one to take that nap is to get her full and use the excess melatonin as another nudge to “Go the #$@! to sleep!” That may also mean supper needs to be right before the bath when the neurotransmitter is maxed out.