Student or Learner
1) Wait a second sir, the server will be right with you shortly and will sit you down.
2) I'm still waiting to be dot down by a server.
3) Server job is to sit customer down.
1. If you would wait just a moment*, sir, the server will be right with you to seat you.
* Wait a second is rude.
2. I'm still waiting to be seated.
3. The server's job is to seat the customer.
Don't sit someone down. Seat them.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.