Typically the best time to start getting ready is during pregnancy. Read a few good books on EC, and join a local support group. Watch a video or two as well. Like with breastfeeding, it really helps to see the mechanics of EC before you try it yourself. Notice how the caregivers respond to the baby and the different ways they may hold the baby at different stages. Ask lots of questions.
Before the baby comes, when you are feeling like nesting, get your supplies in order. You will need something to catch pee in, and something to keep you and the baby dry when there are "misses". Many people pee the baby into a potty or other plastic receptacle. Some babies are peed in the sink, bath or toilet. Many enjoy using the great outdoors. Get a squirt bottle and fill it with vinegar and water or other gentle cleanser to rinse out the pee place after use. When you and your baby are starting out you will need something to keep baby(and you) warm and dry while you are both learning about elimination. Many people use a coverless cloth diaper or prefold when starting out so they can feel immediately when the baby is wet. There are many to choose from. The benefit of having at least a few prefolds is that you can lay the baby on the diaper as you carry him around, making it really easy to notice and respond to a pee. You might also want some thing to put wet and soiled diapers in as well. It is very handy to have some kind of absorbent pad to lay the baby on when he is diaperless, and under him at night.
Rather than setting up all of the diapering supplies in one place, think of having several toileting areas in your house wherever you and baby might be. A potty, a small change mat, a few clean diapers, and some small wipes in several areas of your home works well to avoid always having to rush off to the toilet as infants pee very often! You will likely do this with nursing areas too so you could set up both at the same time. Babies seem to nurse and pee in tandem and in clusters.
When the baby comes, you can choose to start right away, or you can wait while you rest and recover from the birth and get breastfeeding established. You will be learning a lot of new things very quickly and it is up to you when and how to start EC. Do consider that you will have to deal with your babies elimination needs no matter what you choose and it helps to have some of the EC basics in your mind even if you don't plan to start for a few days or weeks.
Communication is the most essential part of EC so start by talking to your baby about what has happened, or is happening. "Oh look, you peed. Now your diaper is wet let's get you warm and dry. It feels so nice to be dry." Always try to keep your communication neutral. The baby will hear how pleased and excited you are in your tone, there is no need to overtly praise the baby for doing a normal bodily function. Conversely, avoid negatives around toileting. Don't make the baby feel stinky, smelly or gross. No one wants to associate their most intimate body parts with something smelly, dirty or shameful. Elimination happens, and we parents have to deal with it. No one place to go is bad or good, it just is and in time all children master peeing in the toilet. Explain the toileting process to your baby. "I think you need to poop. Let's go to the potty. I'm going to hold you so you can poop here. You will feel better after you poop."
Observation is also key to learning about your babies' timing and signals. Try to have some diaper free time in the early days so that you can notice what your baby does just before he pees, and also when he pees. You might notice a certain facial grimace, or a small sound that your baby makes.Popping on and of the breast or being restless or fussy during a feed can be a signal that baby needs to go. Just as you are learning about how your baby tells you that he is tired or hungry, he will let you know when he needs to go. This is where seeing other babies EC can be helpful, babies seem to have a range of signals they use but the themes seem to be common.
Timing is another useful tool for EC. Think about the times of day when you need to go. First thing in the morning, before and after naps, after play and after nursing. These are very likely times to catch a pee. Infants pee as much as 20 times a day in the first few months. Just as some babies cluster feed, they may also cluster pee. Don't be alarmed if you find that your baby does nothing but pee and eat at certain times each day. This tends to slow down as your baby learns that you are responding to his needs, often around the third month. Pooping also tends to become more regular as you and your baby get the hang of EC, so if you offer regular pooping times, and hang out on the potty long enough for him to finish, you might have established a regular pooping habit by about six weeks.
When you and baby are very connected to each other, you may notice some of the intuitive EC cues. The feeling of a warm wet spot when you are hold the baby indicates the need to pee. Random thoughts of pee, or of your baby needing the toilet are common as well. Try not to ignore these intuitive feelings, or you may end up with a wet spot!
Holding on to a wiggly baby over the toilet can seem a bit daunting at first, but with practise you will find ways to hold your little one safely and comfortably. The EC books have good pictures, as do the videos. If you have a local Diaper Free baby group you will likely be able to observe mothers holding their babies to pee. Newborns might like to use a reclining cradle hold, and most babies are very comfortable being held with their back to your chest while your arms support their thighs holding the legs slightly apart. Both boys and girls can spray while they pee. You might have to experiment with your daughter to get the angle right to aim the stream right into the pot. Boys might need a finger to guide their penis down into the pot. Some parents find it is easiest to potty a child who sprays into the tub or shower.
It is important to remember that you don't have to do EC full time, it is more important to establish a harmonious relationship that works for you and your baby. The communication is the most essential part, and you can do that whether your baby is in diaper full time or not. Don't get stressed out about the results, EC is not a contest and there isn't really a finish line, so take it easy and enjoy this precious time with your new little one.
Good Luck and Happy Pottying!