Most GPS receivers do take awhile to latch on to sat signals after being turned-on. It has nothing to do with the displaying device considering that your BT GPS Receiver and BT display device are properly paired. If you're going to use your GPS receiver from a complete powered down state, you should allow a minute or 2 for sat signals to be acquired and processed....
You can install google maps for blackberry for free to get driving directions from your current position (from your BB browser go to
Google Maps and follow instructions for OTA installation), otherwise, you can subscribe to TeleNav or another service provider for voice guided navigation...