A regional sign (word) is not the same as a regional accent. They are two different things. A word (sign or not) is not equal to an accent (a sound).
Five different signs for early...that's crazy. 
Maybe Costello should produce separate dictionaries: one per region. Or at least have websites (like ASLPro or ASL Browser) that do the same thing. And if I may be blunt, having different signs per region is not logical because it only brings confusion to the singer(s). What if an Interpreter had to do his/her duty with two folks from different regions. He/she would have to adjust to cater to each person's known signs. That's nuts. 
