it applies to all times in her life up until the date she fills out the application. the date she became a resident in canada is irrelevant for this question. in her life, has she resided in any other country besides canada? yes or no.
It's asking what other countries the sponsor has called home, where the sponsor lived, and when. The assumption here is that the sponsor is living in Canada (that's a requirement). So anything before living in Canada.
a person can technically be a resident of another country AND hold PR or be a resident in canada as a student or worker at the same time, so it should be up until the date she fills out the application, not just to when she became a resident in canada. the question isn't asking, "before you became a resident in canada, were you a resident of any other country". it is asking "in your entire life up to this very moment you fill out this form, have you ever been a resident in another country other than canada."