Faziq is right, you can land alone and they can come later - the rule is principle applicant need to land first and the dependents can follow - that's a good reminder that you need to understand that each visa is individual, if you complete the landing doesn't mean the dependents can land any time, they have to follow the visa expiry date and within that time frame they can land anytime, but after that their visa will expire and they cannot land even though you will be a PR in Canada.