That is fine if that is the Catholic position, but scripture does not appear to support it:
2 Cor. 5:6-8 : "6 Therefore we are always confident and know that as long as we are at home in the body we are away from the Lord. 7 We live by faith, not by sight. 8 We are confident, I say, and would prefer to be away from the body and at home with the Lord."
As a status in either case, being "in the body and away from the Lord" is directly compared to being "out of the body and with the Lord". This leads directly away from any kind of waiting period idea.
Fifth, intercessionary prayers to the saints and angels are just that: asking those who pray to pray for us in heaven as we ask others to pray for us on earth.
I suppose that I have just never understood the need for this. I agree that God wants us to pray for others on earth, and that it is right and proper to ask someone here to pray for us. We are certain that it happens from personal experience. But to believe that there are saints and angels up there waiting for us to beseech them requires going outside of Biblical teaching. Why not just pray to God? Isn't a function of the Spirit to help you do just that? Do saints and angels have greater "pull" with God? Isn't every minute spent praying to a saint or angel a minute spent not praying to God?
Prayer to a saint is a prayer to God. It is true that if one says "Nah, I will not pray to God either directly or through Mary today; I'll pray to Mary as Mary instead", then he sins. But if one chooses to pray to Mary (or a saint) because he is specifically moved to do so, and asks for their intercession, nothing is taken away from God by that. There are verses that seem to suggest that a prayer of a saint is more efficacious than a prayer of a sinful man ("the continual prayer of a just man availeth much", James 5:16). At any rate, intercessory prayer is just another form of worshiping God, by Whose sovereign grace the saints were elected, and for Whose sovereign grace we plea.
A good example of intercessory prayer is the miracle at Cana where the servant addresses Mary and she intercedes for him with Christ. Another is when the centurion intercedes for his sick daughter. It is possible to interpret either so that to point out differences between them and intercessory prayers to saints, but that would be one interpretation among many.
In 2 Corinthians St. Paul says that we are in the body and away from the Lord, and that we'd rather be out of the body and in the Lord. Nowhere in the passage is an intermediary state excluded.
Are you familiar with the parable of an unmerciful debtor? His debts are forgiven because of his plea for mercy and he is released from slavery. That is salvation by faith granted by Christ. Next, through his own lack of mercy he is condemned again. But the second time he is condemned till his debt is paid in full. His family is not condemned the second time (naturally, they took advantage of the loan but did not participate in the harsh treatment of the secodnary debtor). Thus, the second condemnation is temporary and does not negate the absolute pardon received initially. The second condemnation is to prison, which suggests lack of will, i.e. death. This parable described the intermediate state of payment of debt, or purification, which the Catholics (but not the Orthodox) call purgatory.
The orthodox beliefs differ somewhat, but East and West agree that the beatific vision of the justified may not be immediately available to those who die in faith yet not sactified in the course of their lives.
You are reading the Bible but not asking yourself what you are reading. The Bible speaks of life everlasting. The whole concept of Christ's resurrection is that there is life after physical death, that our souls will be reunited with our new and restored bodies once again at the Second Coming.
We therefore believe, based on what the Bible says, that we are judged upon physical death immediately (cf Heb 9:27), and that those who died in flesh are alive in spirit and that those are destined to be saved at the Last Judgment continue to pray in the heavenly church, because they prayed in church on earth. As such it is equally justified to say "Brethren, pray for us (1 Thess 5:25) to those on earth as to those in heaven.
As Christians we believe that collective prayers are beneficial and we ask of the most reverend of spirits in heaven to pray to God on our behalf. There is Scriptural evidence for this too: "This is Jeremiah, the prophet of God, who loves the brothers, who prays fervently for the people and the holy city." {2 Macc 15:14, Septuagint), but your redacted Bible does not contain 2 Maccabees, so no wonder you don't know.
There is also biblical reference to angelic intercession (Zech 1:12-13).