Seank_: PRL updates may actually happen more frequently than realized. They serve to keep the device updated with regards to contacting the towers of other carriers while not on the Sprint network. Unfortunately, we do not get much, if any, advanced notice as to when device updates will be pushed. You can, however, keep an eye on www.Sprint.com/Newsroom as it may be announced there once a date or date range is set. Jon H. Sprint Social Care Team
I'm aware, I was just noting that just because you get a PRL update, doesn't mean Sprint Spark is coming in the next day or so. That's what I was trying to refer to.
Check out a fun infographic that teaches you how to increase storage, enhance security, improve battery life and clean your device.