It appeared in a work of fiction in 1922: "Why," the man in the brown hat laughed at him, "I thought everybody knew 'Rabbit, rabbit, rabbit.' If you say 'Rabbit, rabbit, rabbit'—three times, just like that—first thing in the morning on the first of the month, even before you say your prayers, you'll get a present before the end of the month."
Today it has spread to many English-speaking countries and in the United States the tradition is common in New England, in particular in Massachusetts, New Hampshire and Vermont, although, like all folklore, determining its exact area of distribution is difficult.
The superstition may be related to the broader belief in the rabbit or hare being a "lucky" animal, as exhibited in the practice of carrying a rabbit's foot for luck.
Rabbits have not always been thought of as lucky, however. In the 19th century, for example, fishermen would not say the word while at sea, and in South Devon to see a white rabbit in one's village when a person was very ill was regarded as a sure sign that the person would die.
credit to Wikipedia