My Silkies would usually start laying again when their chicks were about 4 weeks old. There's a difference between "caring for the chicks" and "letting the chicks hang out near her." By 3-4 weeks, most mama's have the chicks in the latter phase, where they cuddle with the chicks at night, but they don't show them food anymore and they don't fight their battles for them anymore, but the chicks still spend most of their time with mama.
After laying for about a month, my Silkies would go broody again, so by this time her chicks would be about 8 weeks old and by that time - they're on their own.