Simple question about starting streaming websites

This is a really simple question but I don't know the answer to it. Basically I've been reading on streaming websites and already have a good website setup to stream sports but I've also been reading around and have seen some suggestions for ads such as MediaHub as well as suggestions for pop up ads. Basically I need to know if I should first set up my site, get traffic and then get ads or can I get ads from the start? Also, will sites like mediahub approve supplying ads if my website is streaming sports illegally? Thank you, any help would be really appreciated