It doesn't matter when you take it for the first time. You just need to make sure to take it the next day at about the same time you took it the day before. ex: I took the pill yesterday at 5:45. so today i'm going to take it again at 5:45! :D (not really, I'm not on the pill :P) hope I helped :)
I am not sure, it is ok to take it one or two days late when starting on it, but I believe that it throws of your natural cycle in a big way.
Rather just wait till your period and then take it.
Here: This explains why. http://funadvice.com/r/3k2rl27ijs