New plan, retro start date with EACA

[DMcGovern]

Company is establishing a new 401(k) safe harbor profit sharing plan with EACA features.  The plan will have an effective date of 1/1/23.  I'm told no one will start deferrals until 7/1/23, which will also be when the auto-enrollment would start.  Notices would not have been provided to participants until recently (middle of June).  I know you can start an EACA mid-year for new enrollees only, but in the case of this new plan would that still apply?  Or would everyone as of 1/1/23 that hasn't opted in also be auto-enrolled?