Before writing an advert, list everything you did last week. Mark the jobs only you can do, and the ones someone else could do with a month of training.
The second list is the role. Give it a clear title, a pay range you can afford for a full year, and two or three decisions the person can make without asking you.
Plan the first month together: shadowing in week one, running the jobs with you nearby in weeks two and three, and running them alone in week four.