Escaping a PEP and establishing a new single-Employer 401(k) plan

Someone (Paychex) convinced a very small Employer to join a PEP containing an EACA provision in early 2022.  The ADP test fails (terribly) for 2022 so the goal is to get them out of the PEP and establish a new single-employer plan with a more meaningful plan design as soon as possible.

• Can they leave the PEP mid-year (i.e., now) or do they have to wait until 12/31/2023?  The plan document doesn't specifically address leaving the PEP.
• They intend to transfer assets from the PEP to the new 401(k) plan, so would this be accomplished through a 'spin-off' (vs. plan termination)?
• What is the earliest effective date the new single-employer plan without automatic enrollment and including a safe harbor provision can be established?

Any input would be greatly appreciated.  This is all new to us.

Thank you very much.