At the residence where you live and sleep most of the time.
People who live at two or more residences are counted at the residence where they live and sleep most of the time. For example, college students living away from their parental home while attending college in the U.S. (living either on-campus or off-campus) are counted at the on-campus or off-campus residence where they live and sleep most of the time.
Those staying in shelter or living outdoors are counted where they are staying on April 1, 2020.
People away front their "usual residence" on Census Day, like on a vacation or traveling for work, should use their "usual residence", not where they are on Census Day.