I started this activity with J at 13 months. I gave him a bowl of plastic eggs and the empty egg carton and let him try to fill each space. He loved it. It was a great motor skills activity. Eventually I added corks to the mix. He would put the corks inside the eggs, take them out, put them in the empty spaces of the egg carton,… You could use puffs or marbles instead of the corks.
Age: J started aroun 12 or 13 months; If I made it more advanced, he would still play with this today.
Try Again? I used this activity once a week (maybe every 2 weeks) until around 17 months. I could now have him sort colors using the same materials to make it more challenging.
**ETA: Find more plastic egg activities here.