Hey Patrick,
In your mobile-config.js file, you can add a configuration to increase or decrease the duration of the splashscreen.
App.setPreference( 'FadeSplashScreenDuration', 1750 );
Also, I’d make sure all the splashscreens in your xcode project are filled in, not defaulting to the gray Meteor one. That splashscreens file should be in the resources folder of your project.
I’m not sure if there is a better resource for what all the splashscreen config values should be, but I always check this file in the Meteor github repo.
Hope that helps!