Our first two wars under the Constitution were initiated by Presidents John Adams and Thomas Jefferson, two of the principle framers, without the benefit of a DOW. Presidents have been initating conflicts ever since, and no court has ruled their actions unconstitutional.
The Quasi-war with France was initiated by an act of Congress, authorizing American ships to sieze or sink French ships, and Tripoli declared war on the US in the before Jefferson did a thing. Plus Jefferson got Congressional authorization before he sent the Navy and Marines to North Africa.
As an irrelevent asside, neither Jefferson nor Adams were present at the Constitutional Convention, so to call them principal framers is inaccurate. With a little bit of a stretch you can grant Adams the tittle since some ideas from his writings were incorporated into the Constitution, but Jefferson had nothing whatsover to do with it.