Kal Bhairav puja is observed on Kalashtami, the eighth day after Purnima in every month. But the main Kal Bhairav Ashtami is observed in the month of Margashirsh.
Here are some links to download MP3 song of Kal Bhairav Puja for free. Ashta Bhairava Puja is also done on this day.
The second link takes you to download MP3 audio of Ashta Bhairava Pooja.
Kal Bhairo Puja MP3 - Download it from this link
Ashta Bhairo Puja MP3 - Download it from this link