Please see OP2
http://www.cic.gc.ca/english/resources/manuals/op/op02-eng.pdf5.4. Lock-in age of dependent children
The lock-in of age for dependent children is the day CPC-M receives a completed IMM 1344AE
and correct processing fees. Dependent children must be less than 22 years of age when the
sponsorship application is received.
Under 22 years means up to and including the last day before the dependent child's 22nd
birthday.
Offices must date-stamp application forms as soon as they are received.
See [OP 1, General Processing Guidelines] for more information about the lock-in date.
OP1
http://www.cic.gc.ca/english/resources/manuals/op/op01-eng.pdfFamily class: Lock-in (of age) is based on the day that the responsible Case Processing Centre
(CPC) receives a sponsorship application. The documents downloaded to CAIPS from the CPC
will specify the lock-in date.
If age is a factor that makes an applicant admissible, officers should use the applicant's age on
the lock-in date. As long as they are the right age on the lock-in date, they can surpass it before
admission.From the Immigration & Refugee Regulations:
http://laws.justice.gc.ca/eng/SOR-2002-227/page-1.html“dependent child”, in respect of a parent, means a child who
(a) has one of the following relationships with the parent, namely,
(i) is the biological child of the parent, if the child has not been adopted by a person other than the spouse or common-law partner of the parent, or
(ii) is the adopted child of the parent; and
(b) is in one of the following situations of dependency, namely,
(i)
is less than 22 years of age and not a spouse or common-law partner,(or)
(ii) has depended substantially on the financial support of the parent since before the age of 22 — or if the child became a spouse or common-law partner before the age of 22, since becoming a spouse or common-law partner — and, since before the age of 22 or since becoming a spouse or common-law partner, as the case may be, has been a student
(A) continuously enrolled in and attending a post-secondary institution that is accredited by the relevant government authority, and
(B) actively pursuing a course of academic, professional or vocational training on a full-time basis, or
(iii) is 22 years of age or older and has depended substantially on the financial support of the parent since before the age of 22 and is unable to be financially self-supporting due to a physical or mental condition.
So... a dependant child who's parent has submitted an application for Permanant Residence and who has paid the fee's, provided they are both received before the dependant child's 22nd birthday, is "locked in" at that age regardless of how long the application takes to process. They would only need to continue education from before the age of 21 if the application and fees were not received until after their 22nd birthday.
Hope that helps!