I always say, slow and steady wins the race. I usually aim to lose an average of 1/2 a kg a week (anything above that is a bonus). I find this allows for weeks that things don't go to plan.
It's also a great motivational tool to reward yourself when you reach a mini goal, a new CD, a manicure, a new top etc. I find this works a treat.
Good luck on your weightloss journey,