The issue of what happened in
John 20 and in
Acts 2 was addressed by Derek Prince, a Pentecostal teacher, on page 6 of Volume 2 of his Foundation Series books
"...the tense of the imperative form 'receive' indicated that the receiving was a single, complete experience which took place as Jesus uttered the word. It is therefore an incontestable, scriptural fact that at that moment the apostles did actually receive the Spirit.
"In this first encounter with the resurrected Christ, the apostles passed from 'Old Testament salvation' to 'New Testament salvation.' Up to that time the believers of the Old Testament had looked forward by faith, through prophecies and types and shadows, to a redemptive act which had not yet taken place. Those who enter the 'New Testament', on the other hand, look back with clear vision to a single historical event: the death and resurrection of Christ. Their salvation is complete