As far as recognized denominations as we know them today where people intentionally left an organized orthodox group and confession to start a new organized and orthodox group with a new confession, I would think the first would be around the time of the Protestant reformation. The Reformation inadvertently caused the church to realize or to suppose that a new church could be started as soon as a conflict or disagreement arose. Mainstream fear of the clergy was lost with the Reformation. In my opinion, the binding fear towards the Roman church was unbiblical, yet the lack of any fear/reverence among many of the offshoots of the Reformation churches is just as unbiblical.

When I say "orthodox" above I mean Christian/Trinitarian (Gnostics, Mormans, and the like are not denominations but separate religions altogether i.e. non-Christian).

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--chRis
Psalm 115:1

Christopher Reeder
Husband to Kara, Father to Abigail (7), Caleb (6), Grace (4 1/2), Zoë (3), Elijah (1 1/2) and Hannah (born 8/8/2008)

Member: Pilgrim Presbyterian Church (OPC), Raleigh, NC