Pre-Alpha stage for the game of Destiny

During an article about destiny I read that the game is currently in pre-alpha stage. I was hoping if someone could shine some light on how much more work Bungie MIGHT have if it is in Pre-alpha stage. From what I could gather from the google Pre-alpha is before alpha and then it is Beta (yeah obvious). However, beta is pretty much the game is done and things r locked in but they r just ironing out the bugs/glitches. Forgive my ignorance, but if the game is in pre-alpha stage do we have more than 6 months or more to wait for the game. I do not know if anyone can remember from past games they have waited and remember the timeline or of if they have been in the gaming industry to know if pre-alpha stage is a X amount of months away from completion or is it all situational and varies. Surely, someone with knowledge/ background could give an educated guess. I am hoping and presuming the game will release early next year.