Babies are often mentally ready to start talking before they have enough control over their mouths, at a time when they may have enough control over their arms and hands to make simple gestures; a lot of otherwise verbal families have had good experiences with signing. If you look around online for baby sign resources, however, most of what you'll find involves long lists of specific signs, often simplified versions signs from American Sign Language.

If you're just going to have a dozen signs that you use for a few months, however, a lot of the constraints that real sign languages like ASL have developed around aren't relevant. You're not building the foundation for something deep and expressive, you're developing a pidgin with your toddler to help fill a short gap in their capabilities. Which means you can prioritize the specific things your child wants to talk about, and use signs that are very easy for them to create and distinguish.

For example, with our youngest we ended up with, in rough order of acquisition and maybe forgetting some:

• "more": bring hands together twice
• "light": open and close hand twice
• "diaper": tap side of butt twice
• "drink": tap mouth twice
• "pickle": tap side of head twice
• "peanut butter": tap inside of elbow twice
• "ice cream": tap bottom of chin twice
• "bran flakes": tap shoulder twice
• "all done": arms in a "w", wave hands twice
• "lift me up here": tap surface twice
• "outside": raise fist above head
• "umbrella": tap palm twice

These are a mixture of ones we taught her ("more", "light", "drink"), ones she made up ("outside", "lift me up here"), and ones where we started teaching her something but what she ended up actually doing was pretty different ("all done", "ice cream"). Since all that matters is that we can understand each other, noticing what she's doing and going with that is fine.

It's not a coincidence that many of these are "double tap somewhere". Once I realized she was picking those up well I started choosing that form for new signs. It's like, if your child was only going to use verbal speech for a short transition phase and no one in their life already used speech, you might use a lexicon like "baba" / "dada" / "mama" / "nana" / "gaga", allocated to whatever concepts they were most excited about expressing.

She learned most of these signs she around 17m, during a period when she really wanted to communicate but her vocalizations weren't there yet. We taught one sign at a time, using it over and over until she had it reliably. Her older sisters were very excited to help, and would use it too in asking for things. At first we'd always give her what she asked for, and then later sometimes we'd acknowledge it but not give it to her ("ice cream? no more ice cream"). We wouldn't pretend not to understand her to avoid a request.

This period was relatively short: by 20m most new things she wanted to say were vocal, and around 21m she started replacing her signs with vocalizations. At this point (22m) she'll still make some of the signs, but most of the time she'll say the word too.

For comparison, our oldest was very verbal at a young age and only used a few signs ("more", "all done", "open"). I remember less with our middle child, but looking back at videos I think maybe she was even more verbal and only did "more"?

Overall, it's definitely possible to go a lot further than we did with our youngest, but I feel like this level of depth was a good tradeoff for us, and our toddler really enjoyed being able to communicate more.