Ephesians 2:6 says, “God raised (past tense) us up with Christ and seated (past tense) us with Him in the heavenly realms in Christ Jesus.”
Because we are in union with Christ, who is in heaven, then we are in heaven with God. Paul urges praise for God because we are with Him being blessed by Him. As hell is total, conscious separation from the blessings of God, so the spiritual dimension of heaven is total and conscious union with God. In our union with Christ we are already partakers of this spiritual reality, even though it is not fully realized until we are in our glorified state. This means we are already experiencing aspects of heaven, although we are not there yet.
The benefits of this “already and not yet,” Paul has already stated: grace and peace (Ephesians 1:2).