Assuming that it is now when I die and go to heaven, the first thing I'd do is go and see my baby brother that died a few weeks after birth. Then, I would talk with other deceased family members, then talk to God for a while (maybe a year or two). Then, I would go see Adam and Eve, and ask them how on Earth they are in heaven. Then, I would talk with the deceased historical figures I've always wanted to meet.
After all that, I would then rest, and enjoy the splendors of God's kingdom.