Hiring the first person who runs things when you are away

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.