Well, you have to give the stylist some lenght to work with. So your hair should be at least 3 inches long. The ideal would be at least four, but if the stylist is really good he might be able to work with just the extra inch. The long part of the hair in the picture is actually about 2 inches long. Eventhough it seems like it, the frontal hair is not all one lenght. In order for your hair to be able to achieve that spiky look and maintain it, the stylist will sort of twist sections of hair and sort of nip them with the scissors at the middle, but without going all the way through. This will give you hair that is two lenghts conbined. Shorter hair that will result from this techinique will be what will give the longer hair the abiility and sort of support to keep that shape, and make it look natural. If your goal is to have the exact length in the picture, then you need at least one more inch of hair. The stylist can not start with two inches, if that is the final lenght you are looking for. If you just can't wait, then have it done now, and go with shorter frontal hair (about an inch) and just let it grow to achieve the longer look later. But at least you will have the basic cut, and won't be so desparate to have it done.

Good luck, and post a picture so we can see what the final result will look like!