I was thinking of starting a new Q&A, but I don't have any audience (none of my friends are interested).
So, is it okay to start recruiting on Discussions, because there is no other way?
No, this site will not have the community base needed to start a new Stack Exchange Q&A as said in the page for proposing:
When you submit a proposal for a site, it is generally assumed you have access to an audience to build it. Area 51 cannot find that community for you.
I would advice using more external methods beyond Stack Exchange like recruiting the user base from stuff like social medias, forums, other communities and etc who are willing to build the site.
Remember, please don't spam anyone.