Set heap super props before initial page call

snippet.html

<script>
!function(){var analytics=window.analytics=window.analytics||[];if(!analytics.initialize)if(analytics.invoked)window.console&&console.error&&console.error("Segment snippet included twice.");else{analytics.invoked=!0;analytics.methods=["trackSubmit","trackClick","trackLink","trackForm","pageview","identify","reset","group","track","ready","alias","page","once","off","on"];analytics.factory=function(t){return function(){var e=Array.prototype.slice.call(arguments);e.unshift(t);analytics.push(e);return analytics}};for(var t=0;t<analytics.methods.length;t++){var e=analytics.methods[t];analytics[e]=analytics.factory(e)}analytics.load=function(t){var e=document.createElement("script");e.type="text/javascript";e.async=!0;e.src=("https:"===document.location.protocol?"https://":"http://")+"cdn.segment.com/analytics.js/v1/"+t+"/analytics.min.js";var n=document.getElementsByTagName("script")[0];n.parentNode.insertBefore(e,n)};analytics.SNIPPET_VERSION="3.1.0";
// add this line below 
window.heap = window.heap || []; for (var n = ["clearEventProperties", "removeEventProperty", "addEventProperties", "setEventProperties", "unsetEventProperty", "addUserProperties", "identify", "track"], o = function(e) { return function() { window.heap.push([e].concat(Array.prototype.slice.call(arguments, 0))) }}, t = 0; t < n.length; t++) { var r = n[t]; window.heap[r] = o(r)};
// now this works! see https://cldup.com/Z5trhErs9V.png
window.heap.addUserProperties({ testing: 'TEST' });
analytics.load("YOUR_WRITE_KEY");
analytics.page()
}}();
</script>