The American Academy of Pediatrics and the World Health Organization, to name a couple, all suggest breastfeeding exclusively for at least the first six months of a baby's life. That means no water, formula, or anything else that could mess with the internal flora of baby's sensitive gut.
Eventually, they will start eating solid food called "complementary foods," which aren't there to provide too much for the baby yet, as breast milk is still their MAIN source of nutrition. The WHO says the transition period from breast milk to solids takes place between 6-24 months, meaning this isn't an overnight or quick process -- foods are meant to just be introduced slowly.
But when introducing solids to a breastfed baby, you have to find a good balance between the solids and breastfeeding, or your supply can take a hit.
Wait until your baby is ready to start solids: some will be ready at 6 months, others aren't yet. Some people think their babies are ready before, but often it's growth spurts or natural curiosity about Mommy's things they're seeing. Babies like to mimic mom and dad, but that doesn't mean their body's ready for food.
If your baby is under 6 months but wants to grab your plate, offer an empty bowl and baby spoon for them to play with (invisible dinner!), or even consider some frozen breast milk in a mesh feeder (great for teething!). Since we can't see into the intestines of every infant to see if the cell lining of the gut has closed up, we have to go by external guidelines. Your baby is ready to start solids if:
If you've met all that, then go ahead and NURSE YOUR BABY FIRST (always nurse before offering solids) and then try a simple first food like sweet potatoes or avocado. Rice cereal really isn't necessary. If you're going the baby food route, consider making it yourself so you can find textures your baby likes best, or go the baby-led solids route and let baby start out feeding themselves whole, soft pieces with their hands.
Just like with breastfeeding, respect your baby's signals. If they turn their head away, don't open their mouth, or spit food out, just stop. Don't try to play games to get them to open their mouth so you can push food in. They don't NEED foods yet anyway. All food in the first year is really for learning, so the nutrition still is coming from you. Some babies don't want to start solids until they're closer to their birthday, and that's okay.
More than anything, keep up your nursing, always nurse before offering food, and if baby is eating solids well but nursing less, cut back on solids. The breast milk is much more important to their nutrition at this point, and even into the second year, it provides at least half of the nutrition they need, so you've got plenty of time to allow your baby to go at their own pace. Slow down and enjoy it.
How did you introduce solids to your EBF baby?