Question
When are you allowed to start listening to music, and where can I find these laws?
Answer
According to those who are following the “first days” (the first 33 days), that allowance began with Lag B’Omer. According to those who follow the second days (from Rosh Chodesh Iyar until 3 days before Shavuos), the allowance begins 3 days before Shavuos (Sheloshes Yemai Hagbala).