I don't have a regular schedule. Some weeks I will eat it each day, some weeks I won't eat it. The flavor also really depends on the fish. For instance, I liked bass, trout and pompano liver. It was like a big marshmallow like sweet candy. On the other hand, milkfish was the most bitter thing I have ever tasted. I also threw up later in the night from eating rock cod liver... but I think it's because I mistakenly ate its stomach too (plus contents! yuck!).
I'd just go to the local fish monger, get a whole fish, which is presumably pretty cheap, learn how to gut it, and take a bite from the liver. Just avoid the gallbladder or it'll be disgustingly bitter.