Greetings,
That's a good question. I would simply say that the existence of eternity is just outside of the dimension of time. Like a ocean is to continents. So I would argue that heaven and the new creation would both have an address in the realm of eternity. Scripture does say that Heaven will pass away(Matt. 24:35). So it's safe to assume that even heaven, at this present time has a temporal existence. It is one thing to exist within eternity, but it is another to exist eternally.