Hi- The sooner the better when it comes to training babies not to be prop dependent and to sleep independently. The longer you wait the more time it will take to fix all the accidental parenting your little one has become reliant on. If it were me, I would start tomorrow.
My plan was to implement E.A.S.Y. from the time my daughter came home from the hospital. Well, breastfeeding was a nightmare and I could never get a routine going. So, at 5 plus months old, when she was still waking 1-3 times a night, taking short naps, and not being able to fall asleep on her own, I decided I better do something.
It won't be easy, but it will be so much harder later. Good luck!