Conjugal relationship is when you and your partner have lived together for at least a year but are not married. From what I hear, it's a harder avenue to take when it comes to bringing in your loved one, but that's just what I hear - no real fact to back that up.
You said when your girlfriend arrives in Canada you will marry her. Perhaps a better idea is to marry her, and then apply as a spouse. What country is she coming in from? The most challenging part of applying as a spouse is to show enough evidence to prove your relationship is genuine.