Some American practices here:

A Californian of my acquaintance has the "White rabbits" ritual, but believes that it must be said not only first thing, but also while in the act of jumping out of bed -- i.e., while entirely airborne.

A family I used to know from New England said simply "Rabbits," and believed that as long as you say it before you say anything else, you'd be lucky throughout the month. (This is what I've passed on to my own friends and family.)

Finally, a New England-based novel I once read -- sorry, can't recall the name -- mentioned that, to ensure good fortune throughout the following year, the last words you must utter on the last night of the year must be "Hare, hare" -- and the first words the following morning must be "Rabbit, rabbit."

Claire