One night last spring, I took my notebook and my good set of ears to the Village Vanguard for that week’s first performance by the Bill McHenry Quartet. McHenry, a tenor saxophonist with a dry but inviting tone and a history of calmly intrepid lyricism, was working with several assertive partners: Orrin Evans on piano, Eric Revis on bass and Andrew Cyrille on drums. He’d written some new music for the group, which had only ever played one other gig, in the same room, about four months prior. One of those sets had been broadcast on WBGO 88.3FM and npr.org, and I thought it sounded hugely promising; surely this repeat engagement would be even deeper and more accomplished.

I’d come expecting to be bewitched, in other words. But when I left the Vanguard just over an hour later, I was, with apologies to Lorenz Hart, only bothered and bewildered, puzzling over what I’d heard. McHenry played reasonably well, bringing his unhurried wit to a pair of mid-tempo swingers. And there were certainly moments when his rhythm partners brought the coal-burning locomotion I wanted from them. But whenever the musicians pulled away from known parameters-and under McHenry’s guidance, this was often-the focus slackened and the fires ebbed. Oddly, given that Evans and Revis are regular partners (two-thirds of Tarbaby, a slashing postbop band), and that Cyrille is conversant in propulsive abstraction (an acknowledged master, in fact), the band seemed adrift. “The set’s more open-ended moments felt hollow, as if lacking a motive,” I wrote the next day, in a slightly pained, decidedly mixed review for the New York Times.

Well, timing is everything. I was back at the Vanguard the following week to hear a different group, and I ran into the club’s owner, Lorraine Gordon. “You wrote a really great article last week, and I agreed with every word,” she told me. “But!”-she stabbed a finger in the air-“It got so good I couldn’t believe it was the same band.”

Months later I received my copy of La Peur du Vide, an album recorded later during that run and recently released on Sunnyside. Lorraine was right: It’s marvelous, one of the best live recordings issued this year and a manifestation of every hope I brought with me to that disappointing first set. Which raises a familiar tangle of questions for someone in my line of work. Should I have picked a different time to hear the group, later that week or that night? Should I have held my fire until after a second impression? Was it incumbent on me to factor in the need for a warm-up performance? Should there be an implicit handicap for critiquing opening sets, or even an explicit policy against it?

The responsibilities of the workaday jazz critic-a species more endangered than ever, though I’ll wager against extinction-involve several different constituencies. As an informed surrogate for the consumer, the critic’s responsibility is to provide an evaluative compass-not only about what to see but when to go, given that there usually isn’t a price differential between a first and second set. As an advocate for the art form, he or she unpacks meaning, sniffs out intention and attempts to address the music on its terms. There’s also the issue of journalistic merit, and the burden of stewardship for a larger ecosystem, and the cold calculus of a publication schedule. One reason I cover opening nights is that they’re comparatively more newsworthy. Another is that I want the review published soon enough for it to reach all interested parties. When it’s a good review, a few more people end up attending the gig, and everybody wins. When it’s less than glowing, things get complicated, but the intrinsic value of the criticism isn’t compromised-not if you believe in that sort of thing.

The standard rap on second sets is that the musicians loosen up and stretch out. But it’s also been my experience that the second set of an opening night often loses a crucial spark. Once, covering a brand-new project from bassist Christian McBride, I chose to review a second set so that the musicians could settle in, only to hear later that the first had been fresh dynamite, clearly the one to catch. And covering two subsequent sets in tandem has never worked that well for me: I often find myself weighing one against the other (a useless exercise, for readers) or losing the essential point in a glut of information. We all know from experience-and from some exhaustive box sets by artists here and gone-that any jazz engagement has its fluctuations and too many variables to predict an optimal performance. So there is no perfect policy, though in principle I like what trumpeter David Weiss once proposed in an e-mail: “There should be a law that if a reviewer comes to the first show they have to come back later in the run to see the progress and what the thing really could be.” I have done this and rarely regretted it. But there’s always another gig out there, along with other obligations.

A few years ago I reviewed a first-time collaboration between drummer Paul Motian, saxophonist Chris Potter and pianist Jason Moran, three strong individualists with only a few tendrils of shared experience among them. I decided to review the group’s final set, late on a Sunday night, figuring that its rapport would be at a peak. I ended up calling that one right, and when ECM later released Lost in a Dream, an album culled from the run, its exquisite melancholy squared perfectly with what I remembered.

This had been another Village Vanguard gig, and some time later I saw Ms. Gordon, who had the same rapturous opinion of the band. She was gratified by the review, but-well, I’ll give her the last word here: “Why did you have to wait until the very last night?”