My first tip is make sure your Spriter object is not needlessly high res. If you need to scale it down to 10 or 25 percent once loaded, so that it's the proper size, you should use Spriter Pro's feature to create a scaled down clone of your project, and use that one instead, as it will reduce load-time and improve performance.
Aside from that, What I do is add a fade in sprite overlay for the game screen and a loading message which waits for the Spriter object to finish initiating before it fades away to reveal the game screen. If I recall correctly, I just check for the first time the Spriter animation reaches beyond 0.1 seconds.
I'm also pretty sure once a Spriter object finishes loading its ready to go for all future frames... so you could possibly have hidden/off-screen ones loading during your Splash screen/main menu, so that its ready to go in future layouts.
-Mike at BrashMonkey