According to Genesis, Noah waited forty days before opening the Ark’s window.
Genesis 8:6 says that after forty days Noah opened the window of the Ark. He then sent out a raven, followed by a dove, to learn whether the waters had receded. This forty-day interval follows the account of the Ark resting on the mountains of Ararat and the continuing decrease of the waters.
The timing can be confusing because Genesis contains several separate intervals. Rain fell for forty days and forty nights, but Noah did not open the window immediately after the rain stopped. The narrative also records longer periods involving the prevailing and receding waters.
The answer therefore refers specifically to the wait mentioned before opening the window, not to the total time Noah and his family spent inside the Ark. Different translations may vary slightly in surrounding chronology, but Genesis 8:6 gives forty days.