There is an ambiguity in this phrase. It can mean either "when we enter Heaven we are (already) glorified" or "when we enter Heaven (no matter how sinful we are when we enter), we are at that moment and not before then, automatically glorified".
= = = =
I don't think that there is Scriptural justification for emphatically believing either one conclusively.
We can conjecture all we want.
We can speculate all we want.
We can extrapolate all we want.
We can infer all we want.
We can pontificate all we want.
We can stand all puffed up on however many centuries of TRADITIONS OF MAN that we want . . .
but the jury will be decidely out unless and until we get there or unless and until God clarifies it further with emphatic signs following such as a loud booming voice from Heaven heard round the world or some such.
Then Jesus said, "Did I not tell you that if you believed, you would see the glory of God?"
~John 11:40"I have given them the glory that you gave me, that they may be one as we are one: I in them and you in me. May they be brought to complete unity to let the world know that you sent me and have loved them even as you have loved me. Father, I want those you have given me to be with me where I am, and to see my glory, the glory you have given me because you loved me before the creation of the world. Righteous Father, though the world does not know you, I know you, and they know that you have sent me. I have made you known to them, and will continue to make you known in order that the love you have for me may be in them and that I myself may be in them."
~John 17:22-26