Absolutely no one in the universe knows when Apple will definitively do anything until Apple does it. All of Apple's updates, releases and new product introductions are only known internally at Apple until it actually happens.
Anyone who claims to know is either lying or is speculating off of rumor.
There used to be a website that keeps track of when an Apple product was introduced and when it was likely to be updated -- that's about as accurate a "guess" as you're going to get. I can't remember the website, but hopefully someone else will chime in with a link.