Bought a couple of discs from a seller here, however I´ve not received a invoice from him, even after contacting him first enquiring about it. What is the common wait time before I should report him as a bad seller ?

There is a possibility it is going into his SPAM box. It has happened to me before. I dont know how to get around that though if they dont check their box.

Worse case you can ask me to try to connect you two (from my different mailbbox).

Otherwise, after a few days/week, it is usually acceptable to ask for cancellation.

Regards,
Julien

I am about to do that with a few buyers, as a matter of fact, check in your spam box!

Okay, sounds good, I´ll give it a couple of more days