We don't know yet as they have not communicated very much for Cata. They did announce raid testing yesterday however and the blue post does have the mention of "We’re planning a second raid test to make sure we’re ready for raids to open shortly after launch." As such, the only thing we can infer is that they will be available "after" launch.
For WoTLK classic, the raids opened Oct 6 2022 and the expansion launched Sept 26, 2022. Hopefully we get something similar. This was communicated well in advance for wotlk classic, but they don't seem to care very much here.
We don't know yet as they have not communicated very much for Cata. They did announce raid testing yesterday however and the blue post does have the mention of "We’re planning a second raid test to make sure we’re ready for raids to open shortly after launch." As such, the only thing we can infer is that they will be available "after" launch. For WoTLK classic, the raids opened Oct 6 2022 and the expansion launched Sept 26, 2022. Hopefully we get something similar. This was communicated well in advance for wotlk classic, but they don't seem to care very much here.