Garmin makes a device called Tempe, it's a wireless thermometer. It won't work with an Edge device, but I have one for my watch because, you know, having it on my wrist affects the temperature. Tempe broadcasts the temperature every 30 seconds. When they pair, the watch listens for a broadcast, and then syncs the timing, so every 30 seconds it will turn on its radio and listen for a new broadcast, then turn the radio back off to save battery. It takes my watch up to 30 seconds (but usually less) to connect to my Tempe. And it's plain to see why. Maybe that's got something to do with what you heard?

The 800 detects my HRM and PM almost instantly when I turn it on. But it takes a minute or two to power up, read the maps, and have GPS ready. My watch (and cell phone) are already on, so it can feel like an eternity waiting for the thing to boot up.