당신 probably don't need this answered since it's been 게시됨 over a year. But anywho...
In S1E21 'A Trip To The Dentist', Logan says to Aaron: "February," "Wow, 당신 got a vowel right" and "Is this [birthday] party nine months early 또는 three months late?" this puts his 날짜 of birth anywhere from January to March.
According to Logan Echolls' official myspace page found here: link
(PS this site is incredibly interesting.) Logan is a pisces.
Since people with the pisces sign are born between February 19 - March 20
의해 process of elimination Logan cannot be born in January and Aaron clearly got February wrong, therefore his birthday would have to be in March.
If this doesn't help 당신 anymore, at least 당신 can look into his smoldering eyes ;)