I agree with the teachings of Anthony Hoekema, N.T. Wright, Randy Alcorn and others that heaven occurs after this life and occurs in two phases – pre-Second-Coming and post-Second-Coming. The first phase is a spiritual and disembodied existence which the Bible calls “Paradise.” The second, and more glorious, phase involves living a bodily existence on the new earth (with possibly a millennium occurring in between). We will be with God in both phases.
While it’s true that eternal (aionion) life begins in this lifetime, Paul nevertheless stated that to die was gain, so I think it’s best to restrict “heaven” to the next life and beyond.