For your Sobriety Tracker, do you put the last day you drank, or the first day you didn't drink?
Good question. The answer is not so clear. You will have some that are hardliners on one or the other, but you will have to decide. What is your truth? Did you decide that you were done while drinking, or the next day? What day do you want to tell folks?
I put it as the last day I drank, 3/27. I entered rehab on 3/28, and didn't drink any alcohol all that day.
Just remember to always be honest, especially with yourself and you will be fine
For me I use my first day sober. I agree with what someone else said earlier that "whatever your truth is"
I put the day I told my wife!!!… just kidding, not married! I don’t think it really matters if it was the last day you drank or the first day you didn’t. I mean really, are you going to get down to the hour of the first 24 without it? Takes about 3-4 days to get it out of your system anyway! You gonna go with that?? Besides, once you get a few weeks or months who cares? IMHO 

The first day I was sober.
The next day since I was prob drunk when I went to bed.
I entered my first day free of substances, but there is no right or wrong answer. My opinion is that your sobriety starts the day you are sober.
I don't use either.
I put the first day I didn’t drink or use
I put the day I woke up in a hospital. I probably could put the last day I actually drank but I don't know when it was.
1st day I didn't.
You put it for the first day you didn't
The first day I didn’t drink
I used the first day with no alcohol which was 10/3/20.