These $20K freerolls are part of party's 3 billion hand promotion. There will have been 10 of them, 8 are already finished, so only 2 left. The next 2 will happen shortly after the 2,995,000,000th and 3,000,000,000th hand. After the hand hits, you wait a few or 5 or 10 minutes and keep checking the tournaments menu until they show up.