I'd like to know how to define "glorify." How can we conclude that a person is glorified? By what sign?
The word "glorify" means "to give glory to". Glory can mean honor, praise, or devotion, but it is usually considered a much more intense word than any of these. Thus, to glorify God would mean to praise Him in words or to honor Him by deeds. Romans 8:29-30 is used in an unusual way because here God is the one glorifying man. Usually, the inferior being glorifies the superior being. Therefore, we normally think in terms of man praising God. In Romans, God is said to glorify man; the superior being glorifying the inferior being. In this context, it would be best to think of it as God bestowing honor on man. We do similar things in our day. A soldier may do something heroic and the government may honor him with a medal or a ceremony. In English, we would not normally say that the soldier was glorified. We would use a lesser word like honor or praise. However, I think that Paul was trying to stress just how strongly God is honoring man by using a term that is usually reserved for the other way around.
The glory that God is honoring us with is to be welcomed back into his presence. God is so Holy that He cannot tolerate the wickedness of man. We are all wicked and, therefore, all destined to die. It is not the physical death that we are really interested in; it is the eternal death that will not allow our souls (the part of us that survives after our physical death) to enter into the presence of God -- also known as heaven. God has honored us by telling us that He will let those, who have faith in Jesus and become Christians, come into His dwelling place. It would be like being a poor beggar on the street and being welcomed into a palace and being treated like royalty rather than being treated like the scum we actually are.
What makes this so special is that we not only don't deserve the treatment that we are getting, but Jesus is the one who made the whole thing possible. He became the punishment that we deserved. Someone had to be punished for our sins. God allowed his Son to take on that punishment. He said that punishment was so severe, that it was good enough to cover the sins of everyone who willingly wants it (I Peter 2:24). In that way, God determined before we were even born (i.e., "predestined"), that there would be a collective of people who would be allowed back into His presence. His only stipulation is that you genuinely believe in Jesus as the savior. This belief is more than just an acknowledgment that He exists, it is a whole life change that says we believe so strongly that He was the perfect sacrifice that we change our lives to be like Him in every way. We have to be a devotee of Jesus. If we are devotees, then we can come into the presence of God just like Jesus is allowed into the presence of God (II Corinthians 4:14).
The ultimate glory does not exist until after our death. However, in this life, we are told that our lives would change. For example, in Galatians 5:22-26, Paul tells us the kind of people we will become. "But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law. And those who belong to Christ Jesus have crucified the flesh with its passions and desires. If we live by the Spirit, let us also keep in step with the Spirit. Let us not become conceited, provoking one another, envying one another." This is our sign that we are on the right path.