score:2
According to the official website, it is the application date that counts however, the requirement is civil partnership OR marriage OR 2 years living together.
The "easiest" alternative for you would be entering a civil partnership / marrying where you live and getting the appropriate Apostilles and translations (if applicable) of the certificate as proof of relationship instead of trying to prove 2 years of living together.
I don't know where you both live, so you can check here if there are any additional requirements to get the partnership / marriage recognized in the UK
You only need the paper, so there is no need for a whole ceremony / reception and etc...