The way I work my deposit is the first person who places the deposit gets first pick , second person gets second and so on.. I do require that you make a choice on the sex. But if at the time you come to pick and I have both available you can change your choice..
I do not show my puppies until 8 weeks and at that time you can pick or if you wish to wait until they are 10 weeks,( which is when they will be ready to go) You can choose then.. Some people that come along way will do that.