I did taper for a week before I stopped – that was very difficult at least for me, to stop the drinking prematurely that was hard to do . I then had 9 days before I went to work, I did not have any huge physical problems – but I was rather vulnerable and unstable the first month.
If I were you I would prepare for the 7th , try to moderate as much as I could and maybe also train the body a little for the walk. I would not drink freely and start my walk with a hangover.
I use similar thinking to mecanix when it comes never or day of the time. I do not intend to drink again, but I do focus on one day of the time. I do sign in to the 24 hour thread when I wake up, more or less the first thing I do. I do not believe I have missed a day since I stopped drinking.
I do hope you will have a good hike next month.