How can I move the time stamp to the bottom in this heatmap?

I was under the impression the bottomAxesContainer would do the trick, but it doesn:

var heatLegend = chart.bottomAxesContainer.children.push(am5.HeatLegend.new(root, {
  orientation: "horizontal",
  endColor: am5.color(0xfffb77),
  startColor: am5.color(0xfe131a)
}));