Service businesses like yours will have issues with labor increases. It's not insurmountable, but some effort will be required to run things more efficiently.
Scheduling, staffing levels, reviewing the productivity of employees, all could be areas to focus on. Paying haircutters hourly when they have no appointments is wrong. Scheduling patrons for pool assignments instead of just for one stylist is another.
For example, stylists that make $25 per hour should earn you $50. A check of each person's productivity will identify the profitable employees and service mixes.
I would also look at staffing levels, since eight stylists in a store seems like a lot for what is likely 77 hours open a week (10 am to 9 pm). If all are full time, that implies for stylists on duty all the time. Salons I work with do well with three. You might have two extra stylists in each store.
Raises in the minimum wage will only impact those who do not yet earn $15 per hour. But, I suspect that increases in the minimum will cause employers like you to cut the number of employees.
It does mean that you should look at productivity and profitability by employee.
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