I've been saying Holiday 2024 and I stand by that for now. I'm not too keen on March releases because that pretty much means that it would hurt their holiday sales for the prior year (ex: if it releases in March 2024, it would likely be announced before Holiday 2023 and hurt sales that holiday). Worked for the Switch because the Wii U was dead and 3DS was limping along (also the Switch was not backwards compatible with the 3DS whereas the Switch 2 would hopefully be backwards compatible with Switch).
Also, they have a strong lineup this year, which means that the dev teams releasing games on Switch this year won't have stuff ready for Switch 2 probably until 2025 at the earliest (we could at least see Mario Kart in 2024 and then get games like Animal Crossing in 2025, Pokemon & Mario in 2026, Zelda in 2027, etc.).