I'd suggest this, which I think has been said elsewhere in this thread:
Pay yourself a monthly amount and don't touch the rest. And base that amount on a figure that's somewhat less than the average of what you've been pulling in for the last year or so.
Have a crazy lucrative month? Great! Into the "business" account it goes -- you get paid the same amount. Have a crap month? No worries -- you get paid the same amount.
You've got to figure out techniques to smooth the unpredictable into the predictable. That's how you remain sane as a freelancer. And I've been freelancing for basically the entirety of my career, since the late 90s.
Also: Never put yourself in a position where you know you're going to have no savings. That bit about taking three months off and having no savings at the end. Ugh. Personal projects are great. Vacations are necessary. But as a freelancer, you have to earn those things.