I want to change my Apple ID but it’s not letting me

From:

Change your Apple ID - Apple Support

- There's special instructions if you want to change your Apple ID to an @icloud.com address.

"If you try to change your Apple ID to an @icloud.com email address that was created within the last 30 days, you will be asked to try again later."

Additionally, there are apparently restrictions on using an an e-mail which has ever previously been an AppleID OR has ever been used as a Recovery/Notification e-Mail for an AppleID.

Could one of these situations possibly apply?