Answer
You should be aiming to lose around 1.5lbs per week. This is safe, sensible and importantly it is more likely you will keep the weight off.
It is not unusual to lose at a rate of more than 1 kilo/ 2lbs a week in the first few weeks, but this will level off and an average of 1.5lbs per week over the duration that you are losing weight is good, sustainable progress.