I dont see any reason to believe there would have been a heaven until after the fall.
If by “the fall”, you mean the fall of the angels, then I won’t argue with you. But if you’re referring to the fall
of man, then I would disagree, since at that time there would already have been angels in Heaven…and, for that matter, Satan and his demons in Hell.
I thought the general understanding was that Lucifer was cast out of heaven when he rebelled against God?
That’s somewhat of a common misunderstanding. You could say that Lucifer and his demons were cast out of
the heavens, but even that’s really something more allegorical/poetic, since Lucifer and the rest of his demons (who are not physical beings) didn’t literally fall out of the sky. The thing is, if Lucifer
had been in Heaven (if he
had seen the Beatific Vision), then would not have been
able to rebel against God, since he would have by definition already made the choice to follow Him. Since angels have a pure intellect, they are capable of making a perfectly informed decision, and therefore any decision that they make is final and irreversible, simply by their nature…they can’t even
want to change their minds, because there’s nothing else out there that they could discover (that they didn’t already know when they made the decision) that could make them want to change their minds. Therefore, none of the angels were actually in Heaven or Hell (which for them is really more of a state of existence rather than it is an actual physical location) before they made their decision to either follow or rebel against God…it simply something that followed as an immediate consequence to their choice.
Further in general I thought theologically, heaven is generally considered the beatific vision; if that is the case, then heaven by definition is as eternal as God is.
I guess I would agree with you. It’s just tricky when there’s no one else besides God Himself actually experiencing the Beatific Vision…whether or not it would be correct to say that Heaven already exists, or rather that it more properly began when the first angel entered into it. I’m not really sure, but I would tend to agree with you if I really had to make a decision.