It's about timeliness, folks. As in, each of the theme answers has three words that can be used in front of "time" to make a commonly used phrase. We've seen this done before with two word theme answers, but this might be the first time I've seen it done with three.
Do I want to pick a few nits? Sure, why not. What's the point of these blog posts if we don't dissect every little thing? So...
First, TRIPLETIME. Yes, it is "minuet meter", or waltz meter or mazurka meter. Although I'd be more likely to call it "three-four". "Triple meter" googles better. But that's a little thing. It works for the puzzle's theme, for sure.
Second, LONGLOSTFATHER. Huh. Yeah, I guess it could be a "recurring soap opera plot device". I have no way of knowing if this is that common, because I don't watch any soap operas. I certainly think of long lost twins, so this is probably not a stretch. It just feels ad hoc, unlike the other three answers, which are more likely to be in common usage.
The best is definitely ABOUTLASTNIGHT, because it is a real movie, and it had Demi Moore and Rob Lowe. Who by the way is outstanding in Parks & Recreation. Also apparently Elizabeth Perkins and Jim Belushi.
1A: Fritter away (WASTE) gets a B+, just because it reminds of Time by Pink Floyd. "Fritter and waste the hours in an offhand way..." I also love SLITHY! What an unexpected addition. In general the fill is pretty good. How about 3D: Congress (SEX)? How many of you saw that coming? I think the fill shows Mr. Chen's fine eye for avoiding most ugliness. ABLE and EVER get a pair of cute clues from how adding a syllable to their beginning creates a synonym. Good stuff over all.