I mean, I would expect him to have a few ideas. If you're the subs, I would expect you to have opinions and apprehensions, not exactly plans and fleshed-out fantasies ... but maybe that's just me and my experience.

I think you have to talk about your pacing. Will you dive right in and play a heavy scene, or are you going to play some strip monopoly with some spiced up rules so that you can get comfortable around each other.

Also, you girls should decide if you would like to meet in private in advance. And yes, possibly also in the bedroom. And depending on what you want this to be, either as a 'first out of many' encounter, or more as a pre-flight check where you decide if you're all clear.

As to positions: Well, all of them. Somewhat easier to make one sub the super-sub that assists the other two, but all other variants can work as well. One word of caution, I advise against competitions. Losing like that can stick around in one's mind for a long time. Equally, go soft on humiliation. It's not the same safe space if there's a third person around.

Lastly: Each one of you can chicken out at any time. You should maybe think about if you want any of this as a safeword, such as: Let's get dressed and talk, or: I want to be only with my partner now and talk the day after. As usual, it helps to know that the safeguard exists.

... and also, if you want to roleplay any of this, shoot me a thing.