
I'm surprised you don't have any answers yet. I wouldn't start weaning until at least 3 weeks, and even then just a taste. But then I didn't have 11 pups, so that might make a difference as they may need a bit of supplementing earlier if they're too much for mum.
Hopefully someone in a bigger breed or breed with larger litters will see this and be more helpful.
I tend to start mine with a bit of mince (I used Natural Instinct Puppy Mince this time and they loved it). Give them a meal of mince then let mum take over. And I also started supplementing with some puppy milk for them to lap just to supplement mum, but only after 3 weeks or so.