Is it worth hiring my first employee when my house cleaning business does $120k a year on my own?

The question is not whether you can afford the wage; it is whether the hours exist. If you have a waiting list or regularly decline new clients, those hours already exist and the hire converts them into revenue. If you would have to take hours out of your own schedule to give them work, you are paying someone to do jobs you were doing for free.

Pay for travel time in the calculation. An employee paid 30 hours a week will rarely bill all 30, because driving between houses is paid time. Planning on about 25 billable hours from 30 paid is a safer starting assumption than assuming every paid hour is sold.

The loaded cost matters more than the wage. Payroll taxes, workers’ compensation insurance and paid time off typically add 20–30% to the hourly wage in the US. Use your own figure; the break-even moves with it.

The hidden return is your own time. Once the employee covers their own wage, every hour of yours moved from cleaning to quoting, scheduling and selling is an hour spent on the part of the business nobody else can do.