I have a collection of the complete Dvořák symphonies, which I usually listen to in order from the beginning. They say the early symphonies are rubbish, but I was still excited to listen to them the first time: they say the same thing about Tchaikovsky's, but of these even the first three are fun works. But Dvořák's really aren't--they're dull affairs, completely missing the evident genius of the latter works.
So now, when I listen straight through, I try to pick out the point where the symphonies go from bad to good. With Tchaikovsky, this is ridiculously easy. The leap in quality between the third and fourth symphonies is plain as day*: fun work gives way to masterpiece. It's even easier with Beethoven or Mahler or Brahms, who didn't write bad symphonies. Mozart did, but that's because he wrote his first one two months before being born.
With Antonin, the matter's fuzzier, but I peg the third movement of the fourth as the first showing something engaging and interesting, and by the first movement of the fifth, we've definitely reached quality.
*We're taught to avoid clichés, but what alternative sounds better than this? "Crystal clear" or "night and day" would be equally bad; "very clear" gives the same meaning, but there's also an admonition against the use of "very" -- and "plain as day" at least has an earthy feel to it that the Latinate "very" lacks, the latter always giving a sense of desperation ("I mean really really clear, here!") -- and "pellucid" would be pretentious, as would working in any foreign language synonym, whereas non-stressed alternatives: "clear," "evident," "obvious" lack the punch needed. "Is as clear as the composer was gay" is rather gangly.