step 260 b and 311 b is billy's starting path, if you skip his path in step 260 b then you won't be able to do 485, if you did do them steps, then it's 335-338, 386-393, 448-451, 485, if you skipped it all, you can always reset his path by going into the hallway, c+h to pull up the cheat menu and reset billy's path if you want, but then you will have to go through the walkthrough and make sure you don't skip anything, that's including the blowjob's at the pool, etc, but you can also give him photos from the pool by using the cheat menu, after steps 260 b and 311 b, start with 228 up to 338 and then 386-393, 448-451, 485.