Genesis says Noah waited seven days before the Flood began after entering the Ark.
Genesis 7:4 records God’s announcement that the Flood would come in seven days. Later, Genesis 7:10 says that after the seven days, the floodwaters came upon the earth. This interval is a distinct time marker in the narrative and occurs before the stated forty days and forty nights of rain.
The seven-day period is sometimes overlooked because the forty-day rainfall figure is more famous. It also should not be confused with the total period that Noah, his family, and the animals spent in the Ark. Genesis includes multiple chronological statements, including the date when the waters began and the later date when the Ark came to rest, so each number answers a different timing question.