It depends on a lot of things.
What diet are you doing?? How much do you have to lose for starters
I have aimed for 1lb a week. I never understand people who think that isn't fast enough...
1 lb of fat is 3500 calories worth which works out at nearly a day and a half of meals or about 6 hours of cardio so losing 1lb a week is a good achievement in perspective. The recommended amount my doctor gave me is 1-3 lb per week and no faster so I'very been aiming thereabouts.