45-day notice requirement for safe harbor correction

Employee made deferral election upon beginning employment in September 2020.  Recently discovered that no deferrals were made from September through December, 2020.  When new plan year began and employee completed annual enrollment forms, proper deferrals began January 2021.  Since we just discovered the missed deferrals, we cannot meet the 45-day notice requirement under the safe harbor correction method.  Should we go ahead and make the 25% QNEC plus earnings and give the employee notice and move on or must we correct under the regular method for missed deferrals?  Thoughts?