Citing a source that is yet to be published in a conference proceedings I wanted to ask how IEEE cites a paper that is submitted to a conference, approved BUT is yet to be published. 

For example, Author A gives a talk entitled Title B in Conference C which is supposed to take place 5 months from now. But the article is accepted already by the conference organizers. 

I tried googling it but I was confused on how the answers came about.
Just cite it as you would normally, but add a note stating it will be presented in the future.

Just make sure you get an advance copy or a final draft to have some solid basis for any claims you do on it. You might want to state this in your note in the bibliography. Also make sure to update the reference as needed.