That's pretty lame, the author didn't even say which sacraments he's talking about! Here's my idle speculation from what I've learned about what Protestants assume about the sacraments here on Christianity.SE.
The first two would probably be Baptism and the Eucharist.
The first to be added must be Holy Orders to establish apostolic succession to keep up with the demand on the first two sacraments.
The next thing probably was Confirmation since that's a most ancient and apostolic thing to do to a baptized person.
Then come what may be seen as the functions of the episcopate: last rites, reconciliation and matrimony (even though it's not something a priest does).
In any event, it's a pretty much a red herring to even consider this question as having anything to do with churchy developments over the years. The emphasis on the seven sacraments is about God's mysterious presence being felt and His covenants with us as individuals. It's not about numbers and or a gradual deepening in the Church circles (like degrees in freemasonry).