Q:

How to say: When are we meeting? 

How would I say "When are we meeting?"  in the context of asking a friend who I am planning to see e.g. tonight. 
This should be really easy but I can't seem to find a way that sounds 'French'. 
I tried things like:  

Quand nous nous rencontrerons? 
Quand nous réunirons-nous?   

A:

Even more informally than Dahlai's suggestions :
On se revoit quand ? 
... sounds more living, native (spoken) French to me. 

A:

A natural way to say it could be:

Quand est-ce qu'on se retrouve? 

This is more informal but probably suited to the context if you're asking this to a friend.