Dont you know that any visa should be extended before the current one expires. It clearly says that you have option to extend 30 days before and not sure how come you were told about 90 day rule after the status expires(which is illegal stay and then applying to restore even when there is a rule to restore the status).
https://www.canada.ca/en/immigration-refugees-citizenship/services/application/application-forms-guides/guide-5551-applying-change-conditions-extend-your-stay-canada.html
"For any permit, you should always apply at least 30 days before your current status expires. "
