Two questions about crafted gear

[Aethaeryn]

You'll usually see the level-cap gear show up on the MB right after they add it to the game. For Stormblood, I believe the 320 set was added at the same time as savage released in 4.05, which was four weeks after the launch of SB. I imagine it'll be the same with Shadowbringers. Due to the mad rush of players buying/selling the gear for diving into the new savage raid tier, that gear is usually available (at inflated prices) within a day or two depending on server population.

Now that world visit and buying things off of the market boards on other worlds is a thing, it's hard to say when prices will stabilize. Maybe a month or two? Someone who is more savvy with market board trends than I can probably answer that question better.