I wouldn't recommend you get on the scales at all during the week if you can help it. Try to stick to the weekly weigh in! Having said that - you'll probably see a difference after just a day or so but of course that won't be fat loss, it'll be water.
After the 1st week a lot of us notied a rather strange but common phenomenon whereby the scales at home didn't budge for about 5 days - some even went up! So we all got paranoid that it wasn't working etc etc etc only to find a sudden drop in the last couple of days. This is why weighing weekly if you can possibly manage it is the best idea. x