One pair of hands has a ceiling. When you are turning work away, working seven days, or doing jobs badly because you are rushing, you have hit it.
Getting past that ceiling is a skill of its own, and doing it badly costs more than staying small. Plenty of one-person businesses have been killed by a first hire.
Three things have to be true, and if they are not, fix them first:
Your first help does not have to be an employee. In order of least risk:
Most people jump straight to the last one and then panic when a slow month comes.
Not a contract from a lawyer. A page, or even a text message you both keep:
Writing it down is not distrust. It is what keeps a good relationship good when something goes wrong, and something will.
There are real rules about employees versus contractors, taxes, and insurance. Those are questions for an accountant, not for this guide and not for the coach — and they are worth one appointment before you make anyone regular.
Write the checklist for a job. The actual steps, in order, the way you do it. Give it to them and do the first one alongside them.
Then check the second one and the fifth one. Your name is on the work whether you were there or not, and a customer who gets a worse job the second time does not blame your helper.
Every job now costs you what you pay them plus supplies. Work out what is left on each of your services with a helper on it. You may find one of your services does not survive a second pair of hands — that is not a reason to give up on help, it is a reason to raise that price.
Tell the coach what you pay, what a job pays, and how long it takes. It will do the arithmetic with you and tell you plainly whether it works — and it will say so if it does not.