I agree with what other people have said about periods of uninterrupted sobriety. I have 5 months clean today. But you if subtracted the days I had used over the last 18 months I would have 22.5 months clean which makes no-sense at all really. It's not the getting clean that's the hardest part in my opinion. It's the staying clean. Once you get honest with your therapist you can get honest with yourself. Once the honesty kicks in then you will find that slipping isn't such a major thing in incredibly early recovery. It happens. But if that slip makes you want to work harder for your recovery then it has done some good.