Theoretically, the entire sphere does not need to be constructed in an hour. They just need to put in place the piece that blocks the light we see. Depending

Theoretically, the entire sphere does not need to be constructed in an hour. They just need to put in place the piece that blocks the light we see. Depending on how far away the star is, the speed of placing this block in place could be doable (at least within the context of a society sufficiently advanced to build a Dyson sphere in the first place)