That would be hard to pull off, as the contestant that's in third place selects first in Double Jeopardy. For a contestant to 8x their score, they would have to be in a distant third, get the next to last clue in the first round correct so that they get the Daily Double, still be in last place even after their score is doubled, then select the correct clues to start Double Jeopardy. That would be nearly impossible.

So wait, when do they get their daily doubles? At the end of each round where they have the most money?