Is it true that?

More or less from the time you set out to have the surgery after all is said and it done that it takes 6-8 months before the surgery is performed?  That is insane to me because my doctor told me to start the 1200 calorie dier right away.  If I start that now and have to wait 6-8 months more or less to have the surgery I will be at my goal weight then at that pace.  This is the main factor that is on my mind about this surgery I am very impatient I am sure I will find this out tomorrow but I just want some more insight.