I think you are 'out of the woods' when you choose to never drink again, no matter what may happen. It can be an hour after your last drink, or a year, that is up to you. Some never make that choice, and my opinion is that I don't think they are ever 'out of the woods'. My experience is that I quit once, and once and for all. I made my commitment without any conditions so that nothing could ever happen to allow me to drink again.

I wasn't out of the woods until I stopped thinking alcohol was a good thing that I was missing out on. Until that happened, I was really just white knuckling it until I relapsed. The difference now is that if someone told me that all my health issues were gone and that addiction would no longer be an issue, I still wouldn't pick up another drink because I fully understand that everything I thought alcohol did for me that was positive was a lie or was something I can do better sober. For example, going to a party sober a few times helped me realize that alcohol does not actually make people more fun or interesting. You just think you are fun and interesting when you are drunk and think other drunks are fun too. When you are sober you realize that drunk people have boring, repetitive and circular conversations that they don't remember even a half hour later (hence them being circular. So many conversations are repeated word for word). You don't really connect with those people, you just pass the time with them. Also the idea that booze help relax you is just a straight up medical lie. Alcohol is what causes the anxiety, it does not cure it, not even for a few minutes. We drink with the promise that we will be happier in a few minutes, but even if we reach that mythical relaxed state with alcohol, it lasts about half an hour and then we either need to drink more or we start the hangover process. I am done with the ups and downs in my life.

Five years ago, I might have said I was done with drinking, but seeing other people indulge made me jealous and angry. I was angry that I had a problem and angry that I couldn't just have a few like other people. Now I see those people and feel a passing sympathy for them knowing that I will wake up clear-headed and energetic tomorrow and they will wake up with a headache. Living sober means I get so much more out of each day of life. I wouldn't go back to being drunk if you paid me. That said, I will probably continue to work on my sobriety and my mindset for the rest of my life. Complacency can be a dangerous thing for me.

Out of the woods is a very tricky concept. The bitch of this thing is for many of us, one drink and you are right back, whether you have 1 day sober or 20 years. I think it is fine to congratulate yourself on what you have done so far as it is incredible. You can be more confident in the tools you use and the way you live without alcohol as they get stronger with time and you may think about drinking and even recovery less often. I think by definition an alcoholic is never truly out of the woods. Doesn't mean you have to live in fear, but do be vigilant.
Edit- just over 6 years for me.