While Jett can no longer use Tailwind reactively and will need to manually activate a 12-second window before dashing, players may find that her dash is refreshed sooner than expected.
The Jett nerf refreshes her dash more quickly in Valorant patch 4.08
In patch 4.08, pressing the Tailwind ability key will no longer result in an instant dash. After a short delay, players will instead have a 12-second window within which they can actually dash. Tailwind is also consumed, whether or not the dash is used.
The ability also refreshes after two kills, just like before. However, the kicker is that simply activating Tailwind starts the kill counter. This means that if you find a kill and dash immediately, you only need one more kill before you can use Tailwind once again.
In comparison, pre-nerf Jett would still have needed to find two kills after securing that first pick and dashing. So while you may not be able to dash instantly, you may be able to do it more frequently.
Overall, the Jett changes in patch 4.08 put her in a pretty good place in the game. It forces players to finally plan ahead about when to dash and work on gathering information, while still retaining her explosive ability to take space on attack.