How long do you stay employed by someone else?

Hi Steve,
In your book, you often refer to the role played by your partner, Dave, whereby he continued to do his day job while you devoted more and more of your time to your property investment business. This seems necessary in the early stages not just to maintain cashflow, but to convince the bank you can repay any mortgage you need to finance the acquisitions. Even when contracting in a profession like IT, the bank wants 2 years of tax returns, regardless of how much you are pulling in. The fact that the contract has an end date really turns banks off from lending.
How long do you think it would be necessary, assuming one wanted to duplicate your success, for at least one, if not both, people in a relationship to maintain their current “working for someone else” employment status?
Do you have any tips – places to go to for mortgages, for instance – for people who have contracting incomes but not tax returns for the last two years, or for the best way to shorten the time you end up spending working for someone else? I include contracting as ‘working for someone else’, since ultimately you need some company to agree to buy your time. So not much different to permanent employment.
Thanks
Kat