Is Paul being a pattern for believers retroactive to Pentecost?
No. The pattern is not retroactive to Pentecost. Scripture says 'hereafter,' meaning from Paul's conversion on the road to Damascus onward, God would call people into the Body of Christ. It does not reach back to Pentecost; the pattern begins at that point, not before.
Les explains that Paul is the chief of sinners and the sinner saved by grace, the head of the line, number one. The pattern is for those who would believe 'hereafter,' not retroactively. It does not go back to Pentecost. From Paul's conversion on the Damascus road onward, God began calling people into the Body of Christ, which Les notes is a strictly Pauline revelation not found in the Gospels, Acts, or the Old Testament.
Howbeit for this cause I obtained mercy, that in me first Jesus Christ might shew forth all longsuffering, for a pattern to them which should hereafter believe on him to life everlasting.
More Questions
Why does the Bible call Paul a pattern rather than just an example?
A pattern must come first, before the things made from it — just as with cutting cloth or lumber you don't make a bunch of pieces and then decide to draw up a pattern, since the pattern precedes and is then followed.
Why does Paul call himself the pattern in 1 Timothy 1:16?
Paul is the "pattern," and a pattern by nature comes first and is then followed — just as you don't cut a pile of cloth or lumber and then draw up the pattern afterward.