Originally posted by HMTTKB
You mention "restore" and not update. I am kinda confused. Are you saying that I back up my phone and then restore it via iTunes on 8.3.
First things first. Back up your iPhone (so you have all your stuff, photos/music/apps/notes etc.
Update to 8.3 firmware. Once that's complete, click restore and choose the back up (will be the most up to date one).
Now jailbreak.