Hi
In her application, she will need to fill out the information about you (spouse) and dependants (children). check the box yes where it says Accompanying to Canada. They will automatically include you guys if she is approved and you can all come at the same time. When approved, the embassy will give you the paperwork for the medical exams for the ones accompanying her.
God bless you!
Ensure that you request an Open Work Permit for yourself and pay the fees when you submit her application.
PMM