There is no such thing as a day 0. Think about it. After you relapse you already start again. Therefore it’s day 1.
If you think of it as a "streak" then the first 24 hours after whatever you are stopping would be day 0. I think of it more as a plan and as such this is day 1 of this new plan that I just started.
Day 1 because you relapse and you go through day 0. You born with 0 years old. Then at first year you are 1 year old (because you have lived 1 year of life)
Think about it, if you're zero, you haven't lived a year, but it's your first year living, if you know what I mean.
Of course, you're living your first year, when you have 1 years old, then you're living your second year haha. So if you relapse you're on day 0, living your day 1
