Miami head football coach Mark Richt gave a detailed breakdown of how he eats a sandwich. Watch his philosophy of how to take one apart in 10 bites:

His diagram:

According to his method, bite three of both halves would certainly be the most anticipated. Bites one, two, four and five would be difficult to predict given that the ingredients are not as concentrated on the edges of most sandwiches. Of course, unknown variables are the type of sandwich and the accuracy of the middle slice.