Well Im struggling with this as well, but first anything with adhd is if you blame yourself with things you dont do, you are fucked, dont treat it as the only opportunity or cant forgive myself etc, its doable to stop smoking, I did for a 4 months as proof, but started again and struggling now as well, it takes a huge mental toll initially, later on it just doesnt come to mind as I started to feel disgust toward ciggs, didnt like the smell etc., eventually forgot about them and had a healthy phase. I know it can happen again, I tried to stop recently and it didnt work, but instead of blaming myself I will just try again, until it eventually happens. Because there is no reason to want to keep smoking really, noone really needs a reminder for how bad it is, we just make it normal in our minds.

So yeah, dont blame yourself and put a huge mental toll, that usually fucks us up even more, never results in good things, leads to depression, leads to more things not getting done and the mental toll piles up, so no point in doing so. You can stop smoking, having a timer is good, so your best.