I think it makes most sense to talk tiers when:
A) People have a strong sense of, and are making use of, most of characters' tools
B) People have maybe 85% of matchups solidly down, meaning that they know what to do in almost all common situations vs. the cast
C) There is plenty of high level vs. high level actual match experience to back up the claims
before then, it's pretty rough guesswork. To me it feels like a lot is unknown right now; a number of characters don't even have basic flowcharts yet, even some of the better characters don't have all of the matchups charted well yet, and some of the cast has hardly been explored at a high level.
I'd think it will take at least 3-4 more months before high level representatives of all the characters start appearing and there's enough cast vs. cast info to even begin a sensible discussion that's not based on gaps in information.
Also it'll help once the various regions start meeting each other at tournaments like ECT, UFGT, and EVO, and you add the tourney wisdom + the endless hours of casuals.