How much of my money should sit in safe fixed income versus everything else?

There is no single right number, but the honest starting point for a founder is that you already carry enormous risk in one illiquid, undiversified asset: your company. That argues for keeping your personal money noticeably safer than a salaried person's might be. Many founders hold a solid base of safe fixed income, their emergency fund plus a comfortable buffer, before putting anything into equities or other risk. Think of the safe layer as the thing that lets you keep going when the startup has a bad year, not as where you get rich. How big that base should be depends on your runway, dependents, and how much of your net worth is tied up in the company. This is a general frame, not advice for your situation, and since returns and tax on these instruments change, confirm specifics with a qualified advisor before committing.