Most puppies at that age chew because they are bored. In order to fix the chewing, we have to fix the boredom! Increase his current exercise program by at least 30 minutes and make sure his toys and chew bones are being rotated so they stay new and exciting. He should also have access to several interactive toys such as food cubes and Kongs. Additionally, if a dog tends to chew a certain type of material when being destructive (wood in this case) try to find a toy with similar texture. If the problem persists, you can also spray the table with anti-chew spray.