If you haven't filed before her work permit expires, then she should stop working at the end of her permit. Include an OWP with the application, and she can start working again after stage 1 ( 8 months from now) - that's for the working part.
You also need to make sure she stays with a legal status. Technically, you can still sponsor her while she is out of status, but do everything possible to avoid that - it will save you time.
So : if you can't file the application before her work permit expires (and can not be extended), then at least apply for a change of status from a working permit to a visitor visa. Explain that you are soon applying for PR, and include the proofs. If you can, pay already the application fee for the PR application and add that as a proof. She will have implied status and can legally stay in the country until she gets her visitor visa. Try and file the application soon, so if she gets the visitor visa, then she will have implied status continuing with the PR.
GOod luck,
Sweden