Myself and two other engineers working for a Fortune 500 company knew we really wanted to start a high-tech product company, but were not exactly sure what the idea was yet or how we would fund it. To mitigate risks, but to start the "resource allocation" process, we decided we would first start a consulting company to help replace our incomes while we spent extra time on the business concept, the business plan, and getting funding. We also decided that profits (excess revenue after our agreed salaries) from the consulting operations would be saved to provide seed money for product development.
When all three of us quit our jobs, we each put up $3K of seed money from savings to allow the company to get established and pay rent, etc. until it could sustain itself. We also accrued our salaries as a liability against the books until the company could afford to pay us. It turned out that we did not get any salary at all for 3 months until the first real consulting check rolled in. From there it took about 3 more months (month 6 or 7 since founding), until the company had "made good" on our "back pay" since quitting our jobs.
We spent most of the first year of operations simply consulting to stock pile some cash cushion in the company bank account. At the start of the second year, we then started brainstorming and working the product business plan phase of the company as an "in house" consulting project of sorts. It took two years to identify the idea and build a business plan around it before actual development of the product started and then another year from there to raise the initial round of outside funding.....(we were attempting to raise money just as the dot com implosion was occurring, but we did eventually raise money over the course of a few rounds)
Relative to the original $3K investment, it wasn't until about at year 10 since founding that I got that back (plus the capital gains on it of course) when company and its investors had a successful exit via an acquisition of the business.