Rule 72(t) allows you to take substantially equal periodic payments from your account based on a rate called the applicable federal mid-term rate (in fact, at a rate equal to 120% of that rate). After you start the payments, you can't stop them or modify them for 5 years or until you're 59.5, whichever comes
later. That rate is affected by the same economic forces that allow 3% mortgages and keep savings accounts and CDs paying .2% interest. Right now, the 120%AFR is a peensy 1.06%, so you need absolutely incredible sums of money to support even a modest lifestyle (try
this calculator: $800k in the account yields a pair of 45-year-olds $20k-25k/year). In summary, Rule 72(t) and SEPPs aren't going to be a feasible way to get money out of the account for a while yet.
What you can do is roll money from traditional 401(k)s and IRAs into Roth IRAs. You have to pay income tax on any money converted that way, but then after it sits in the account for five years you can withdraw any portion of the money that was principal (not earnings) without penalty or tax. The year you retired, you could roll over enough money to survive your sixth year of requirement; the next year, the seventh, and so on. Then, all you'd need to do is figure out how to survive the first five years of your retirement. (You could use money already in your Roth IRA, money in brokerage accounts, consulting income, or real estate proceeds, for example.) That method seems to be a bit more practical, as well as very tax-efficient.