The ideal time to start is anytime from birth to 4-5 months old. During this time, there is a window of learning open. You can start by using the following four steps.

Step 1
The first step is for you to spend time observing your baby. Anywhere from 1-2 hours should suffice. This can be done in one afternoon. Lay your undiapered baby in a comfortable, warm and safe place, then observe her:
a) timing (how long and how frequently she goes after waking or feeding)
b) body language (such as twisting or grimacing while defecating)
c) sounds (such as grunting while defecating)

This can also be done using a sling. In fact, babywearing is one of the best ways to become familiar with your baby's elimination timing and patterns since you know straightaway when she goes. It is especially beneficial in cold climates or rooms without sufficient heating. Some mothers keep their babies naked in the sling, carrying them skin-to-skin, which keeps baby at a perfect body temperature. If so desired, you can keep a cloth diaper under her while in the sling. It is, of course, not a requirement to keep your baby naked in the sling. Even if she is wearing some clothing and/or a cloth dipe without a waterproof cover, you will know when she goes.

Step 2
The next step involves using your powers of intuition or logic in reading your baby. Anticipate when your infant needs to go, then at that moment, make a watery sound such as "sssss." Alternatively, if your baby starts to go while you are observing her, immediately make the "sssss" sound. Within a few days, your baby will associate this sound with elimination. 

Step 3
Now you need to try some different positions and toilet places to find what works best for you and your baby. When you think your infant needs to go, hold her gently and securely over your preferred toilet place while giving an audible signal ("sssss" or whatever sound/words you prefer). Your baby will soon associate the sound, position and place with elimination. Use whatever location and receptacle are most comfy and convenient. Examples include the bathroom sink, a mixing bowl, a basin and the outdoors. Older babies can sit between your legs on the toilet. There are many other positions to try, including the ones depicted in the two sketches on the home page of this site.

Step 4
From now on, pay close attention to your baby's elimination communication and elimination timing. Work as a team with your baby and ENJOY!