hi,
I dont know whats the standard, but here is our experience.
My parents were DQed separately (NVC okayed one doc for mum but rejected it for dad so had to resubmit)
I guess that put them on separate tracks as they both got different ILs. Then the Montreal Embassy, also approved my mum easily, yet asked my dad for original documents.
I assume if the parents file stayed together at the NVC level, then so does everything else that follows.
Now if your dad also happens to get an IL and your mum hasn't had her own interview yet, you can call the scheduling service to request an appointment together. We choose to go through with my mums as we did not have any clarity of my dads timeline.
hope this helps.
