Retirement tax questions

So the age to start the first RMD did not rise to a higher age for this 2024 year. I am asking this because last year in January 2023, it was 72 but when I turned 72 in May 2023, the age had been changed to 73. Logically it makes sense to work the year from January to December but the Secure Act 2.0 has an obscure notation on how it breaks down the birthdate year based on a different calendar which is how RMD are decided and dispersed, especially the first dispersal . I was told that it is decided during the time of the last quarter of the year (between October through December) and is dispersed the following March of the next year. After the first dispersal then you can decide when you want to receive the RMD after that. Can you clarify?