If they aren't eating hard food now, they should definatly start- most weaning is between 4-6 weeks, but it usually happens naturally. Usually Mom starts feeling the teeth when they nurse, so she stops letting them nurse. Try introducing the food, and the should start eating it. A bit of milk is fine, but since they'll be adopted in a couple weeks, I'd definatly make sure they are fully weaned by then
They eat solid food. They eat kibble, canned and raw. But they still nurse ALL the time! Should I seperate Momma from her babies or will she eventually wean?
As long as you aren't planning to rehome them immediately, I would just let mom wean them naturally. She'll let them know when she's tired of the whole deal.
My kittens were still nursing quite a bit up until 10 weeks. Goldy didn't start to seriously wean them until they were about 8 weeks even though they were eating solid food. They're 8-1/2 months old now and every once in a while still want to nurse. Goldy lets them for 2 or 3 minutes, then gets up and walks away.