I use the baby whisperer books too and think EASY is a really good routine. It really does help read your baby's cues. On days when it's gone wrong for some reason, it's so much harder to read baby's cues and understand what she wants. It's useful to understand your baby's temperament too. My baby is definitely spirited, as described by Tracy (can't remember her surname) and this has helped me understand her needs for sleeping i.e. has to have all stimulation removed, go to sleep in the dark and follow a sleep ritual (adapted from the BW book).
I would say though that the routine didn't really start happening until about 6 weeks. LO needed to sleep more and EASY didn't really fit her needs. Good luck.