I didn't know when my day one was until I was sober for several months. I knew it was time to put down the drink on many occasions before I finally did but, instead, I continued to add unnecessary suffering to my life and the lives of others. I was completely broken down by the time I dragged myself to detox. I never circled a day on my calendar in anticipation of stopping, nor did I ever attempt to moderate my drinking. Screwing around with planning and moderating would have cut into my drinking time. I knew I was a drunk, and so acted accordingly.
There may come a moment for you when you know it's time to stop. Disregard it at your own peril.