Once the tops of the mountains had become visible (Genesis 8:5), Noah let 40 more days pass:
Then it came about at the end of forty days, that Noah opened the window of the ark which he had made; (Genesis 8:6)Over the next 21 days, Noah sent a raven out of the ark once, and a dove out of the ark three times. The first bird Noah sent out was the raven:
and he sent out a raven, and it flew here and there until the water was dried up from the earth. (Genesis 8:7)Noah waited 7 days, and then sent out the dove for the first time; this fact can be implied from Genesis 8:10, which describes the second time Noah sent out the dove (emphasis added):
So he waited yet another seven days; and again he sent out the dove from the ark. (Genesis 8:10)From Genesis 8:10, it can be concluded that Noah sent the dove out (for the first time) 7 days after he had sent out the raven— and after 7 more days had passed, Noah sent out the dove again.
Thus over the first 14 days, Noah sent the raven out once, and the dove out twice. Genesis 8:12 tells of the final time that the dove was sent out (21 days after the 40 days had passed):
Then he waited yet another seven days, and sent out the dove; but she did not return to him again. (Genesis 8:12)Take a look at the chronology of the flood graphic below in order to see the complete chronology of the flood.
The Chronology of the Flood: The Final Months - Genesis 8:13-19
The First Sight Of The Post-Flood World - Genesis 8:5
How God Stopped The Flood (Part 1) - Genesis 8:1-3
The Ark Comes To A Rest (Part 1) - Genesis 8:4
Evidence for a Global Flood: Water Above The Mountains - Genesis 7:19-20
To view a larger version of this graphic click here.