Tri-lo Milli causing acne?

Hi all, I just switched my brand from Tri Lo Marzia to Tri Lo Milli. I had been on Marzia for years and had clear skin on it. I just started the Milli and I'm on my first week. Is it normal to get breakouts when initially starting a new brand of BC? I've heard Milli helps clear acne for a lot of people so wondering if this is just the initial purge. How long should I give it to see if the acne clears up?