But he that is joined unto the Lord is one spirit.
1 Corinthians 6:17 (KJV)
The moment we gave our lives to Jesus we were spiritually united with Him. We are joined unto the Lord in that the individual members of the body make up the body as a whole. He is the head, and we are His body. This means that in the spirit we are already made perfect in Him, and the more that we embrace this reality by faith before we can see the evidence of it, the more of His glory will we see in and through our lives.