Blizzard has announced that the Inspiration Catalyst will unlock 6 weeks after the Mythic raid opens in Dragonflight Season 1, similar to Shadowlands Season 3.
Blizzard
Acquiring Set Armor in Dragonflight
When Sets returned as a major endgame feature in 9.2, we debuted the Creation Catalyst as a tool for players to access and complete their sets, with the following goals: