In Thirteen E-Z Steps
1. Indulge in a couple of months of mounting anxiety/paranoia about availability of local Pre-K slots, via rumor on neighborhood listserv, playground chats, in line at Fairway, etc.
2. Realize that if you pay your current (private) preschool what it's asking for another year, you'll never forgive yourself. Convince yourself to bank on the public system. Attempt to dismiss rising anxiety levels and believe that despite increasingly wild speculations on listserv (playground, Fairway, etc.) all will be well. Eschew paying massive nonrefundable deposit and enjoy three days of self-righteous satisfaction ("We're not the kind of people who need a fancy-pants preschool").
3. Plunge into renewed anxiety. Realize you might wind up with no preschool at all next year unless you have a good "back-up" for your zoned school, in case the rumors of skyrocketing demand turn out to be true. Wonder if your fancy-pants pre-school can be persuaded to keep you on a waiting list even without a deposit.
4. Research back-up schools in case zoned school doesn't work out.
5. Discover the insufficiency of your research tools.
6. Discover the one thing you can learn about each potential back-up school is that
  a. it will be a bitch to get a kid there and back five days a week.
  b. it has even fewer pre-K slots than your neighborhood school.
7. Treat mounting anxiety with
  a. moderate amounts of red wine.
  b. network television.
  c. mutually supportive conversations with other parents going through the same thing, resulting in increased anxiety for all concerned.
  d. large amounts of red wine and network television.
8. Phone neighborhood school and all back-up possibilities several times. Create a spreadsheet matrix of the conflicting answers about times, methods, and durations of Pre-K regristration periods. Annotate with contingencies as outlined by officials at regional and district offices. Include statements from the school, periodically posted online, which contradict all of the above.
9. Consult matrix whenever anxiety level drops into reasonable state.
10. Allow the fact that all registration will occur in a desperate one-day blitz, in which one's "place in line" at each back-up school will be determined by when you get there with child in tow, to penetrate last undamaged redoubts of brain.
11. As "PK-Day" approaches, formulate battle plan for attacking list of schools. Play-dough, toy trains, and Playmobil figures may be employed to map out assault strategy. Realize that the person smart enough to market software allowing parents to automate this process would make enough money to hire freaking Mary Poppins.
12. Assemble birth certificate, immunization record, maternal grandmother's horoscope, power bill, tax return, bag of properly sorted recyclables (rinsed), and six proofs of purchase for Veggie Booty.
13. Consult weather, assemble good-behavior bribes and join the Amazing Race. On the big day, try not to get carried away.