This is a common question we all consider when starting to sign with our baby and it’s highly personal. This means there’s no correct answer. Some parents might only end up teaching their baby 5 or 10 signs and then consider that good enough for them to get by. They’ll teach common signs used throughout the day and ignore other signs that might be less practical though equally as useful such as animal signs, activity signs, signs for various toys and so forth.
I recommend that signs be continuously added as your baby grows and their interests change. At first, you should focus on necessities such as MILK, EAT, WATER, ALL DONE, DIAPER and so forth. This will help make your job easier and life more pleasant for your baby too. You might then add a few signs that interest your baby – these might surprise you. They may end up being FAN or LIGHT, but might also be something more understandable like CAT or DOG if you have them around.
From there, you should consider adding a few more signs that help with routine (“routine signs”) like SLEEP, various common foods and so forth. Next you’ll graduate to anything and everything your baby gravitates toward. These are called “motivating signs” and can include just about anything, but are usually animals, machines like TRUCKS or AIRPLANES, or even DOLLS.
A toddler can learn just as many signs as a parent is willing to teach them. My son was over 100 signs at 16 months of age and he continued to add signs as quickly as we could come up with them. Signs we used more rarely were forgotten and this is the real issue with teaching a lot of signs. It’s a use it or lose it game, so if you want to continue to grow your baby’s sign vocabulary, you need to continue to use the signs yourself and have your toddler do the same.
If you decide that you only want to teach 10 signs, so be it. Teaching signs is wholly dependent on your available time and your level of interest. What is important is that you don’t try to out-compete other parents, this isn’t a race. And while our son hit a high benchmark with his signs, it was only because he had two highly dedicated parents. Don’t make any number your goal, just go with the flow. If signs are easy for you and your baby and it makes you happy, then continue to add more, but don’t feel that your baby needs to learn a certain number of signs.