Which day of the Lord is Peter speaking about in II Peter 3:10?

II Peter 3:7 But the heavens and the earth, which are now, by the same word are kept in store, reserved unto fire against the day of judgment and perdition of ungodly men.

 10 But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up.

 12 Looking for and hasting unto the coming of the day of God, wherein the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat?

 13 Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness.

Is this not speaking about after the thousand year kingdom of Jesus upon the earth?

In line 12, it says, "the day of God", describing essential the same thing.

So, is the "day of God" the same as the "day of the Lord" in line 10?

Clearly this does not sound like the same day of the LORD which describes the second advent, though amillennialists would say it does.

However, it also says, in line 10, that the day of the Lord will come as a thief in the night.

Will the end of the thousand year kingdom come suddenly and unexpectedly?