Madame, I am going through this process too
ATM! I'm on day 3. I had to go cold turkey too (anything else wouldn't have worked).
I've only expressed very little just once on the 1st day, because I thought I could feel a lump on my breast. It was rock solid hard on the 1st day and very painful, I lay down on my back pretty much the whole day (DS is being looked after by his dad).
2nd day it was still rock solid hard but I felt a little more confident that I wouldn't get mastitis. I just had a bottom shower and haven't showered top half of my body and haven't been out!. I'm also not walking around as movement increases milk supply and pain.
I'm on third day now, and the breast is still v hard but slightly softer so I hope we are going in the right direction?! Anyone know?
Things I am doing:
- cold green cabbage leaves around the breast (put them in the fridge or freezer). I change them every 2-3 hours. This helps reduce supply and inflammation.
- for the 1st day, cold compresses from freezer.
- sage tea around 6 times a day
- vitamin b6, 200mg per day for 5 days
- Benadryl plus capsules, 3 in 24 hours. This contains pseudophedrine which helps decrease milk supply by 24% per day apparently. You can get them over the counter at a pharmacy, make sure it's the one that contains pseudophedrine or get any tablet that contains that.
Regarding expressing, I've read alot online, and spoken to people too, who have said only express if the pain is unbearable or you spot signs of mastitis (like red patch on breast, or blocked duct or feverish etc). There are some online who are suggesting that as long as you don't empty the breast it's ok to express. I really need to dry up the milk ASAP as we are on holiday next week, so I'm trying to do the fastest method, though I have no idea when it will go! 
Best of luck and keep us updated x