Here is some information on the number 17 used in the Bible to support the date February 17, 2012. The excerpt is from the link.
The number 17 signifies "vanquishing the enemy" and "complete victory in Christ." During the days of Noah, God vanquished rebellious mankind by the flood which He began on the 17th day of 2nd month. The ark came to rest on the 17th day of the 7th month. Jesus was victorious over death when God raised Him from the dead on the 17th day of the first month.
The 17th time love is mentioned in 1Corinthians 13, it says, "[The] greatest of [all] is LOVE" (verse 13). Hence, the love of God (John 3:16) is victorious in all things. True believers will be victorious over death at the resurrection (1Corinthians 15:54-55).
The beasts of Daniel 7 have 7 heads and 10 horns, totaling 17. The beasts symbolize world-ruling kingdoms from Daniel’s time to the return of Christ — kingdoms which reign victoriously over the nations that reject God’s rule. Revelation 13 depicts Satan’s end-time system as having 7 heads and 10 horns, again totaling 17. The whole world will worship Satan and the Beast, and no one will be able to make war against him (verses 4, 8); he will make war against the saints (verse 7) and have a temporary victory over them:
"Then I stood on the sand of the sea. And I saw a beast rising up out of the sea, having seven heads and ten horns, and on his horns ten crowns, and on his heads a blasphemous name. Now the beast which I saw was like a leopard, his feet were like the feet of a bear, and his mouth like the mouth of a lion. The dragon gave him his power, his throne, and great authority. And I saw one of his heads as if it had been mortally wounded, and his deadly wound was healed. And all the world marveled and followed the beast.
"So they worshiped the dragon who gave authority to the beast; and they worshiped the beast, saying, "Who is like the beast? Who is able to make war with him?"
"And he was given a mouth speaking great things and blasphemies, and he was given authority to continue for forty-two months. Then he opened his mouth in blasphemy against God, to blaspheme His name, His tabernacle, and those who dwell in heaven. It was granted to him to make war with the saints and to overcome them. And authority was given him over every tribe, tongue, and nation.
"All who dwell on the earth will worship him, whose names have not been written in the Book of Life of the Lamb slain from the foundation of the world." (Revelation 13:1-8, NKJV)
The saints will ultimately be victorious over the Beast when God raises them from the dead at the first resurrection (Revelation 15:2; 20:4).
On the 10th day of the 7th month, the Day of Atonement, Satan is bound (Revelation 20:1-3). Thus, 10 + 7 = 17, depicting Jesus Christ vanquishing Satan.