Custom searchStore watch for results

I’m using a custom searchStore in my component. Once I have set up all the parameters, I call the start() method to run the query. I immediately then set a flag that is watched by another component that renders the results like so:

this.boostSearch.start();
this.searchRun = true;

the problem is that this triggers the rendering component too quickly. But this works fine:

this.boostSearch.start();

setTimeout(() => {
  this.searchRun = true;
}, 100);

but this is obviously a crude fix. How can I watch to trigger this component to render once the results are in?