This has happened before. Check this thread. The problem was fixed, but I'm not sure exactly what fixed it. It seems to be related to the particular WiFi you are attached to. Anyway, here is the thread:
I just bought my NOOKcolor today, and the display time is 8 hours faster than my actual time! I've played around a bit and can't seem to get it to straighten out! Any advice would be greatly appreciated!
Do you happen to live in California? 8 hours would be the difference to GMT (+0).
Is your internet access working OK? And did you set your time zone properly when you set it up? If so, you could try rebooting the unit (press and hold the power button until you get the shutdown message, confirm, wait for shut down, then power up by pressing/holding the power button again). The NOOKcolor sets the time by accessing a time server and setting the time based upon your time zone.