In our Montessori classrooms, we have in place chopsticks of different lengths, different make > ie. melamine, porcelain, wood, (etc) and different colours to entice children... especially the young ones to work with. We try our best to source for materials in complete sets to provide opportunities for easy to difficult range, on our shelves. However, if it's for simple home use, you may use whatever material you have at home to work with your child.
Just like introducing the pencil grip for the first time, we can also allow for opportunities where children can exercise their pincer grip with varied materials prior to the actual pencil... like painting with paintbrushes, painting with pegs & sponges, cutting exercises, transferring activities using tongs, (etc).
Ideally, we will initially provide bigger and lighter objects for the children to lift with their chopsticks. Like those colourful wool pom-pom balls, then slowly upgrade to perhaps, rubber balls followed by glass pebbles.
When you observe that the children have a steady hold with the chopsticks you can then practice sorting activities with a handful of similar items; by color, by size, (etc) Objects should be lifted and transferred carefully and softly into sorting bowls or trays.
After which in our classrooms, we also have the occasional party days when we have party noodles for snack time and let them all practice with the chopsticks!. To ensure it is not an activity whereby they are forced to perform or show they MUST or they CAN work with the chopsticks, we also place a plastic spoon and fork set for them to use in case they get tired using the chopsticks.
Do bear in mind too, that while it's a normal to write and hold chopsticks, each person will have a different hold to it. It doesn't matter what style they have as long as the pincer grip is good, not too awkward and they do not drop anything they eat... especially noodles... it can get messy.
It is still work in progress with chubs and dragon_boi..