18 year-old male, looking to undergo permanent hair removal. If I try Lightsheer Duet in Sep, will I see final result by summer?

Thanks for your question.  The Lightsheer DUET is an excellent laser hair removal system.  The ideal candidate has darker hair. Usually 20% of hair is removed with each treatment.  Treatments are repeated every 6 weeks on the face and every 8-12 weeks on the body. This allows for effective removal of hairs in the anagen phase.
As always, an in-person consultation with a board certified dermatologist with cosmetic training is the best way to assess your needs and provide medical advice. 

The LightSheer DUET laser is an excellent choice for removal of dark hair in a fair-skinned person.  About 20% of hair is removed with each treatment so several treatments are necessary.  Treatments are done 8 weeks apart on the body and 6 weeks apart on the face.

There are several excellent laser hair removal systems on the market, and the LightSheer Duet is possibly the best as far as the combination of safety, excellent hair reduction, and the least amount of pain. Speak with your dermatologist to ensure the best system is used for you.