change button bootstrap button text before rendering d3 svg object

I've got code aimed at visualizing some complex data. The user first selects a data file to load; after clicking the load button, the page generates a "plot" button with an onclick event handler with the function renderPlots().

When the user clicks the "plot" button, then all the plots are properly generated and I'm happy. However, in the case of a larger data set, the plotting process may take a few seconds so I'd like to change the button text to something like "rendering..." while the plots are being generated so that the user knows their plots are on the way.

As per the bootstrap documentation for dynamically changing button text, I've tried something like

function renderPlots() {
    $("#render").button("loading");

    rest of code that does all the D3 plot generating...;

    $("#render").button("reset");
}

The problem with the above code is that it doesn't actually change the button text first, it's doing things asynchronously and I'm at a loss of how I can force the button text to change on screen before any plotting actually starts.

Any thoughts?