It is highly unlikely you will break even if you only walk one dog at a time unless you are happy to ask a high price.
For every hour dog walk it will take at least 90 mins of your time and you have to cost accordingly. Drive to the location pick up dog and drive to walk location. Even if close to you picking up the dog, cleaning the dog off, making sure they have water and are ok to be left takes time.
You have to have insurance and also all my employees have dog training qualifications not so much to train people to train dogs but to make sure the dogs they are walking are safe to walk and not pull on lead etc. They also have all done a course on body language and first aid course. In my mind this is vital is walking other peoples dogs in public places.
Dont underestimate the money you will spend on equipment. Our walkers on average need new boots every 3 months and several sets of wet weather gear.
I have the facility to wash down dirty dogs and dry them before putting them back home if they are muddy. I have to have facilities to keep them cool in the hot weather.
All our vans are AC and kitted out to meet our insurance requirements.
Clients want regular walks and if you could not go one day you will lose your clients. One way to get around this is to buddy up with another dog walker and cover each other in emergencies but it is not ideal and again clients dont like it.
We do not walk more than 4 dogs together but do have private land where they are exercised. Working out the groups of dogs and making the timings work is hard work. Invoicing etc after work takes time. Although mine is done online when clients book but that then costs me money to have the app to do this.
All my trainers wear body cams extra expense but vital if any issues arise (and they will!). All dogs are videoed and videos sent to clients during the walks.
It is more than going for a nice walk with dogs - there are a lot of shit untrained dog walkers out there but the good ones flourish and do make money.
If you are going to fit in walking during school hours realistically you will only be able to do about 3 hours work a day. You are not going to make much money.