You can either stay at your day job and build your business in the remaining 120-some-hours left in the week (which is my recommendation) or you can work at your startup, building it full-time.
Don’t get trapped into being enslaved to your startup as this is a bad business model when all roads lead through you.
When starting a business, think lean and don’t spend a dime on anything that is not critical to the success or survival of your business.
THINK ‘PUP TENT’, NOT DREAM HOME. Spend enough to know you have a winning business model then and only then do you begin putting the big money into it.