That infographic is great information to have... BUUUUUT! There's a but, haha. Please don't be fooled into thinking the best time to log in is when the popular models are offline. Remember, they are all online at that time for a reason.
I myself have tried every shift possible back when I first started to figure out what worked best for me. I can tell you for certain that you will tend to see higher room counts logging in at times when the top models are online. However, this doesn't necessarily equal more tips. Perhaps it means more of a potential to be tipped with more people in your room but... eh. Not really, in my experience. Therefore, I think it's a matter of finding what time works best for you and that means experimenting with different time slots and, even better, doing a camathon, even multiple camathons. The bottom line: Whatever times work best for the members that are your regulars is the time you will ultimately want to select and stick to.
Best of luck!