We've finally found someone.

So we've been searching for a third or even just a threesome for a while and now we've found someone, but instead of a threesome it's more of a foursome. I'm in college right now, so due to the virus we won't be able to meet until mid September. Do y'all have any advice on how to approach this? I know I shouldn't be nervous but I am so nervous that something will go wrong or they'll change their mind.