I would just mention it in the interview if they don't bring it up first.
In my personal experience, I interviewed before my two year anniversary but I entered the US after and I was SO nervous when arriving in the country, I didn't want to bring it up and just hope it would automatically update but one of the first things the agent said to me was that as I had entered after my two year anniversary it is now an IR1 and he stamped my passport accordingly.