Definitely a great idea. Working part time while running a company is a great way to raise capital for your growing business. Starting and maintaining a new company takes a great deal of money, and you may not see immediate profits. Instead of borrowing, why not make some cash by working part time?
This is a great way to stay out of debt and give you a sense of accomplishment. Although this idea is a good one, be careful that you are able to pour your focus into the task at hand. Many people have difficulty staying focused at one job, let alone multiple ones. I did this for awhile and the stress almost become too much to handle. The plus side to the argument is that I stayed out of debt and once I learned to balance my career and job, I was able to get enough money to focus on my business full time.
Working for someone else can be the best way to earn money to eventually work for yourself.
Good luck on your endeavors!