The first two chances for you to take an S-Rank Picture come very early in the game.
1. In Case 0 you will see a lot of Zombies behind safety glass, including the first blueprint you find in the game. Simply take a photo or a selfie and you have your first S-Rank picture in the bank.
2. Once you arrive in the Main Mall, follow the mission marker and you will come across the Caribbean Cove. Loads of zombies gather here and you can take an easy S-Rank picture. Make this a normal photo instead of a selfie because you need to catch as many zombies as you can here to earn the S-Rank.