My mamas have all quit mothering around 4 weeks, and started laying within a week or two after. I've read of their mothering a lot longer than this, just haven't seen it. But from what I read, if you remove the chicks, the mama will get quite upset and search for them, and I would think that would cause them not to lay for a while. Maybe your hen will stop mothering on her own by 5 weeks.
Last fall I had a hen in her own mini-coop with her chicks for about 8 weeks before reintroducing her with only a couple keeper chicks to the main flock. She didn't lay all 8 weeks. Since she went in with many other layers, I can't really say when her laying began again.
I plan to cordan her off in a section of the run with a nesting box while she is hatching. I don't want the other 3 hens forgeting about her and then have problems when I try to re-introduce her to her flockmates.
My hen started laying eggs when her chicks were about 6 weeks old. She actually went broody again with them still with her! She had just started ignoring them I guess. Even though I never once saw her peck them, and they stole food from her all the time. Such a good momma