How a woman can ask her fwb for ?

I had with an ex co-worker 4 days ago. The day after that i told him we should repeat and he said that it sounds good, but we havent talk in 3 days and i dont know if it is okay to ask him for or i should wait until he suggests ? How do i ask for ? Do i just tell him hey lets meet on Saturday for or just say lets hang out. I dont even know if we are fwb, we had just once.