Matthew Poole and continuators on Isaiah 20:3

3 And the LORD said, Like as my servant Isaiah hath walked naked and bare-foot three years for a sign and wonder upon Egypt, and upon Ethiopia:

Not constantly, but when he went abroad among the People, to whom this was appointed for a Sign. Some think it was only three days, a day being usually put for a year in Prophetical Scriptures, as Numb. 14. 33, 34. Ezek. 4. 4, 5, 6. But although a day be put for a year, yet a year is never put for a day.

Either, 1. when this Judgment should come; to wit, three years after this Prophecy. Or, 2. how long it should continue; for three years: For some have observed that the Chaldeans spent so much time in Conquering Egypt and Ethiopia.