According to Genesis, Noah waited 40 days before sending out the raven.
Genesis 8:6 says that after the waters had decreased, Noah opened the Ark’s window and sent out a raven. The verse places this action 40 days after the mountain tops became visible in the narrative’s sequence. The raven flew back and forth until the waters dried from the earth.
Noah later sent a dove on separate occasions. The first dove returned because it found no place to rest; after seven days, a second release brought back a freshly plucked olive leaf. A further seven-day interval preceded the dove’s release that did not return. These episodes are distinct from the raven’s first dispatch.
The passage’s time markers can be confusing because Genesis also gives broader chronology for the Flood, including the Ark’s landing and the eventual drying of the ground. The answer to this specific question is the 40-day interval stated before the raven was sent.