What year did Sacagawea join the Lewis and Clark expedition?

When Lewis and Clark wintered at the present site of Bismarck, North Dakota, there they met Sacagawea and her husband in 1804. Toussaint Charbonneau was interviewed to interpret Hidatsa for the Lewis and Clark expedition, but Lewis and Clark (esp. Clark) were not overly impressed with him. However, Sacagawea his wife spoke Shoshone and Hidatsa, so they hired Charbonneau on November 4,1804 and he and Sacagawea moved into Fort Mandan a week later. Sacagawea was 16 or 17 at this time.