What age is best for kittens to leave the nest

Hello just after some advice about homing my kittens. I have 4 kittens that are 10 weeks today, we are keeping two of them and my sister is having the other two. They are still feeding from mum but are also eating solids as well although not a great deal. I was going to let them go today but mum has become ill and so I didn't want too much disruption or to let them go until I know what is wrong with mum in case they have it too. I've been reading it's better to wait until 12 weeks, do you think this would be best? Tia

12-14 weeks is best so they learn all of their kitty manners from mom. It's great that you're keeping them in pairs.

In this moment the question is rather academic, as you are letting them be home, till you know exactly what happens with mom.   So count on the 12 weeks.

Otherwise 10 weeks isnt not bad, so your plan was OK.   But now you should wait, yes.