This is only a prerequisite for the CEC immigration program. The soonest you can apply is when you have one full year of work experience in a skilled profession (i.e. NOC A, B or 0). Note that you cannot count work experience you gained while studying. Also, even if you qualify to apply, this doesn't guarantee you will be selected out of the pool of applicants.
There are other Canadian immigration programs that requires you to have at least a year of work experience, but this work experience doesn't have to be from Canada (e.g. FSW/Express Entry).
Note that if your objective is to get PR, you should take a 2 year program so that you qualify for a 3 year PGWP. The chances of getting PR are low with just a 1 year PGWP.