[MMF] My first time with a couple, advice needed!

OK so first off I don’t know if this is the right place for this post, please correct me if it isn’t and point me in the right direction. I will be following this up with the story after its happened.

So I’ve been talking to a couple for a while, mainly the man amd about how much his wife loves two cocks. I’ve been invited over to join them, they seem nice and up for a laugh. They are also aware that I’ve never done anything like this so are happy to go slow to begin with. For them it’s all about fun and for him it’s all about his wife.

I’m excited but also nervous, she looks gorgeous but is also quite dirty in the bedroom. I’ve never been with a woman and another guy there as well. I’m worried I will embarrassed myself by cumming to quick really.

Edit: just to clarify it’s all completely straight and I’m M being invited to the couple.

Any advice?