My partner told me we don't need to prove 12 months of cohabitation under the common law partner in Canada class because it doesn't say so on the checklist. Only for the family class. I told him since both are common law you need to prove 12 months still. I don't have the checklist in front of me (at work atm) so I don't remember what it says exactly.
Your partner is extremely wrong about this. You absolutely must have evidence to show 12 months of continuous cohabitation if you plan on applying under common law.