Usually within a couple weeks after she weans the chicks.
When they wean the chicks is variable,
as is how long after weaning that resumption of lay begins.
Some broodies wean at 3 weeks, some go for up to 8 weeks.
When they start to lay again could depend on age of hen and time of year.
Sometimes broodies will molt after weaning.
Might also depend on feed and how soon she gets back into condition.