According to Genesis, Noah waited seven days before sending the dove out again after its first return.
Genesis 8:10 says Noah waited another seven days before releasing the dove for a second test. This time, the dove returned with a freshly plucked olive leaf, showing that vegetation was appearing above the receding waters.
The passage repeats the seven-day interval before the third release, when the dove did not return. This timing is separate from the 40 days and nights of rain and from the longer period during which the Flood waters covered the land. Careful reading of the sequence prevents those different time spans from being treated as one duration.