As I understand it, the way it currently works is that if you vote before 15 minutes, then you lose some curation reward - the earlier you vote, the less curation you get. At some of the earliest minutes, you don't get any curation reward at all, it all goes to the author.
However, once 15 minutes has been reached, the earlier you vote, the more curation you earn, because if a bunch of people vote after you it's like your vote "recommended" the post as worthy of an upvote.
So, the most strategic time to vote on a post under the current system is right at the 15 minute mark, if you think it's going to earn a lot of votes.
Under the new system, that mark has been moved to 5 minutes, ostensibly to prevent from happening what @paulag mentioned - where people get to a post before 15 minutes and wait to upvote because they want curation rewards, but then forget to go back and vote it later.
But frankly, with my vote being worth two cents at these prices, who gives a poop unless you're a big fish earning lots on curation? If I earn 0.001 Steem or 0.002 Steem, or less? I don't know. I don't worry about it. It's an orca/whale problem.