How much weight can you lose in 9 months?

This depends on what you do. There is no time frame that could be given because it depends on your size, how many kilos you have to loose to fit into your IBM, your metabolism and most importantly how you go about it. You can go on a crash diet where you will loose really quickely (eg cabbage soup diet) but you will find that it will come back just as quickely as it went and don't be surprised if it is doubled.