OK, here is my best advice. I've been grooming for 15 years now and have a successful (when the van isn't in the shop for over a week grrr) mobile business. I've had it now for over 2 years.
First, there are a select few that can leave grooming school, open their own grooming businesses and be successful. Most are strong business people to start with. The biggest mistake I feel groomers make is thinking to have a successful grooming business they only need to know how to groom. You HAVE to be business savvy as well to make the most of your business. You have to have a solid business plan, especially if you are looking for a loan, and very good credit, and even with that it is very hard right now to get loans when you have no background in the field you are venturing into.
A lot will also depend on what school you attend and what you are able to learn in the short time you are there. There is SO much that goes into being a great groomer and you simply cannot learn it all in the short time you are at school. The best thing to do is to work for at least 6 months, if not a year or more for someone else who can help fine tune your skills. There is more to grooming than knowing your breed standards and the haircuts that go along with it. While working for someone else you will also learn how to deal with clients, different ways of handling pets because one way does not work for everyone, different techniques they simply don't cover in grooming schools etc. Scheduling, time maintenance, safety procedures, the list goes on and on. Chances are when you first graduate your speed will not be there and you may be able to complete 3-4 dogs in a full day. Going mobile that would probably make it even less with drive time in between. You will learn shortcuts and time savers by working for someone else as well. It's invaulable information that will not only make you a better groomer but most likely a more efficient one and therefore a higher earning groomer.
When you do go to start your business you need to have enough money set aside to cover all expenses for at least 6 months. If you buy a brand new unit you will have a monthly payment as well as other monthly expenses such as business and commercial auto insurance, fuel, phone, advertising, water, shampoo and other products used on the pets etc. Plus you will need to have money set aside for you to live on until the business is able to turn a profit where you can start paying yourself. On a one to one basis, the typical business owner makes less than the average employee because you are paying your expenses, not to mention your taxes. As an employee I think you pay 7.3% or something like that, but being self employed you pay double that.
Of course there are great advantages to being your own boss, or no one would want to be. I also have a mobile employee and plan to have additional vehicles on the road in a few years.
I do not want to see anyone fail which is the only reason I am giving this advice. I don't want to seem like a kill joy at all. I certainly wouldn't want to discourage you from your dream, but I do think you will increase your chances of success ten fold if you work for someone else first before jumping right in to your own business. I'd also suggest taking some business courses. Many community colleges offer them at very reasonable prices. There ARE those I know, who are on this board, who have gone right from school to their own businesses who are successes. But in general I do think my advice applies for the majority of people.
What a caterpillar considers the end of his world, we call a butterfly.