How do Premillennialists explain Matthew 25:31-46?

Premillennialists believe Jesus will return, reign with His saints for 1,000 years, and then after the 1,000 years are completed the final judgment of the wicked will happen. Matthew 25:31-46 states that "when the Son of Man comes in His glory, and all the angels with Him, then He will sit on His glorious throne. All the nations will be gathered before Him, and He will separate them from one another . . . ." The righteous will be sent off into the kingdom, while the wicked will be sent off into Hell. And so "These will go away into eternal punishment, but the righteous into eternal life." I'm curious how Premillennialists typically explain this passage. At first blush it looks like it's saying the final judgment happens *right at the Lord's return* -- for both the righteous and the wicked.