What is the best way to position the little round plastic disks that go under a glass top on a table?

I just bought a wood table that came with a glass top to protect the wood, along with the little plastic discs that space between the wood and the glass — presumably to keep the glass off the wood.

What is the right way to space them? More importantly, how do I keep them in place when I am putting the glass on top (man oh man is it ever heavy)?

Any tips or suggestions are welcomed. Thanks for your help.