There are people in heaven that died previously and are there now. That's where saved people go when they die. Not only that, Jesus told the thief on the cross that he would be in heaven that very day. Check this out:

(Matthew 17:1-3 NIV) After six days Jesus took with him Peter, James and John the brother of James, and led them up a high mountain by themselves. {2} There he was transfigured before them. His face shone like the sun, and his clothes became as white as the light. {3} Just then there appeared before them Moses and Elijah, talking with Jesus.

(Matthew 22:30-32 NIV) At the resurrection people will neither marry nor be given in marriage; they will be like the angels in heaven. {31} But about the resurrection of the dead--have you not read what God said to you, {32} 'I am the God of Abraham, the God of Isaac, and the God of Jacob' ? He is not the God of the dead but of the living."

(Luke 23:39-43 NIV) One of the criminals who hung there hurled insults at him: "Aren't you the Christ? Save yourself and us!" {40} But the other criminal rebuked him. "Don't you fear God," he said, "since you are under the same sentence? {41} We are punished justly, for we are getting what our deeds deserve. But this man has done nothing wrong." {42} Then he said, "Jesus, remember me when you come into your kingdom." {43} Jesus answered him, "I tell you the truth, today you will be with me in paradise."

(John 8:56 NIV) Your father Abraham rejoiced at the thought of seeing my day; he saw it and was glad."