Looks like BC was mostly 3 1/2 to 4 months apart. However with Dragonflight launching on Black Friday and the way the holidays fall I'd be highly surprised if it gets launched this year. Plus Ulduar has 14ish bosses and a vehicle fight to debug so that's a lot different than cranking out Zul'Aman.
For reference:
June 1, 2021 Burning Crusade launched, with pre-patch on May 18th.
Sep 14, 2021 The Eye and SSC
Jan 17, 2022 Battle for Mount Hyjal and Black Temple
March 22, Zul'Aman
May 12, 2022 Sunwell
Aug 30, 2022 Wrath pre-patch
Sep 26, 2022 Wrath launch