I start using play dough while teaching somewhere around the age of 1,5 to motivate young children to stick to one place and concentrate. At this age they stop putting everything into their mouth as a first thing to discover tastes and textures and start using their hands to explore. It may be a good idea to start with home made play dough. This way even when the child explores by accident mouthing, nothing terrible will happen.

Receipt for home made play dough:

1. Mix together the flour and the salt.
2. Mix together ½ cup of warm water with a few drops of food coloring.
3. Slowly pour the water into the flour mixture, stirring as you pour. Stir until combined, then knead with your hands until the flour is completely absorbed.

Play dough is great to teach colors, shapes, sizes and textures (there are various textures of clay). Moreover play dough is an interesting tool to practice the pin grip and improve eye hand coordination. I use songs and Cookie monster as  "big helper", who is the only one allowed to eat the play dough. Later on you can customize and expand play dough play with other toys or play dough tools.

Have fun!

More resources how to use play dough while teaching:

https://busyteacher.org/20391-how-to-teach-with-play-dough-9-simple-activities.html

https://www.teachstarter.com/blog/10-ways-use-playdough-classroom/

https://www.edutopia.org/discussion/15-ways-use-play-doh-junior-high-or-high-school-classroom

https://www.powerfulmothering.com/how-play-dough-can-be-one-of-the-best-teaching-tools/