Please find a piece of 6mm acrylic (50*50mm),which used for testing the power of laser tube.You should have one in your toolbox.
If you don't have acrylic, you can cut wood, then tell us the thickness.
Files: cut a 15*15mm circle ; blowing air; keep laser power to 90%,and then test how much is the fastest speed does the laser cut through the acrylic.
Below video link is for reference.
Please tell us your testing and we will judge for you.