Initiating Background Services BEFORE onTimerStart()

I've tried to "registerForTemporalEvent" in the onStart() AppBase method, and in the DeviceView initialize() method. I get an error (at least in the simulator) about Out of Bounds.

It works fine in the onTimerStart() method. But this is to grab a JSON payload from a WebService and I'd like to try to get that data before the user starts their activity if possible.

There must be a way to do that. I don't know what sequence I'm violating by attempting that in onStart() or even in DeviceView initialize()? Where else can I do this before onTimerStart()?

Thanks!