Dont make a big deal about it, it may get him more anxious than needed.
Go to the store and buy the triangle shaped crayons. (Crayola makes some) take them out of the box so he doesnt see they are made for toddlers and give him some PLAIN paper to draw on. White, or colored. You can even cut the colored paper into fun shapes. Or if you think he is ready, let him practice making some snips with the scissors. (another great fine motor exercise!) He doesnt need to color in the lines if he is making his own designs.
You can also get the triangle grips to slide on his pencils. It makes it easier for these little ones to hold.