Before you do anything check your local ordinances to find out if you are even allowed to board pets and if so how many. Find out rules about creating traffic in your area and if there are restrictions on what my city calls "Home Occupation"
When you say you want earn $400-$600/week do you mean gross or net?
If you mean gross you'll have to factor in:
Rover's percentage - so you'd actually have to be generating $500-$750/week. Which is a minimum of $75/day in bookings if you work 7 days a week. Depending what your prices are this is going to mean boarding 3 dogs at a time every day of the week or maybe boarding one dog and walking/drop-in on 3 or 4 dogs per day. Not sure what the ramifications are of leaving a boarded dog alone long enough every day to go out and walk 3 or 4 other dogs. Just something to consider.
Gas - I had to raise my dog walking prices because I realized the amount of time I spent behind the wheel and the cost of gas meant I was making about $4.50 an hour for walking. You might get lucky enough to have all your dog walking clients be within a 5 mile radius but that limits your client pool.
Household cleaning products - This is an expense I had not planned on when I started. Some people lie when they say their pet is house-trained, or maybe they are house-trained... but only at their Owner's house. I have the convenience of a fenced yard. I've had dogs that I let out 8 times a day and still they pee in the house. Luckily I already owned a steam cleaner but I've had to buy all kinds of other products in an attempt to deal with urine stains. In one area of the house no matter what I do the stains keep re-appearing so I had to buy a big area rug to put down when I have guests so that was another expense.
Taxes - If you earn $400-$600/week you're going to have to pay taxes on that amount. The good news is that any of the expenses I mentioned above should be tax deductible.
On the positive side I can tell you that since the very day my profile went live I've had boarding requests in my email almost every day.
Good Luck whatever you may decide
I should add that I live in a very central neighborhood in DC, and would offer all services -- dog- walking as well as dog-sitting.
When I signed up in DC i ended up working with 90 dogs within 9 months of sign up. It was insane