Agreed with many other posters.
My Partners PR is subject to Condition 51 despite having been a relationship for nearly five years as we only lived under the same roof for two of those 4.5 years prior to applying. His work visa kept him in a town that was 350 km away, he used my house as home base on the weekends and as a permanent address, but our relationship was not considered common-law during that time because we didn't live together full time.
It doesn't make a lick of difference, nor do either of us care that the condition is there. We are committed just like a legally married couple and certainly are staying together for far more reasons that his PR status.
Often people make a wincing expression (jokingly) when we tell them that his PR is conditional for two years, it certainly is difficult to have peers take a common-law relationship seriously, people assume we're just "dating" .
Perhaps thats because common-law gets tossed around so much to describe long term relationships? I don't know.
OP, yes you will be subject to conditional PR, but it should be a moot point if you are applying for residency under spousal class IMO.