Hey good luck on your DAT. I'm taking mine a few days after yours, and all I can say at this point is that based on a lot of other breakdowns and posts I've seen, if you're scoring in the low twenties on Topscore, you are probably set to get around the same thing or better!
And speaking as someone who's taken the MCAT before (you probably know this stuff), but try not to stress yourself out the day before the test. If you are going to review stuff, don't do it right up till the last minute. Take maybe at least half the day off and chill and go to bed early-ish. Then in the morning, eat a good breakfast and go for it! You will do awesome I'm sure!