several hours - to speed it up place a bowl of hot water in the bottom and renew often. Newspaper on floor and there may be a drain to open and place a bowl or tray beneath. I wouldn't empty the fridge
ive got all in one fridge freezer, my freezer takes about an hour if that. now i know youll all tell me off but i cant be arsed and dont have the strength to pull mine away from the wall, so i empty it, not the fridge, dont switch it off, put a bowl of boiling water in it leave it 10 mins come back with a spatuala and occassionally my rolling pin to whack the hard stuff and i go for it scraping and smashing the ice. Loads of towels down and a bowl to put my "snow" in.
Quick and easy, especially with 2 kids harrassing me.
yes i know, how far wrong can one person go, but it saves a lot of earache