Gabapin-NT should be taken at bed time usually. Needs to be taken initially at low doses better 1/2 tablet for initial few days followed by full dose to avoid sedation, drowsiness next day  as it is most common side effect. Can also cause mild dryness in mouth bcoz of nortrypyline  component but usually will fade off. Hydration and relaxation exercises. Sleep hygiene and proper posture while sleeping and working.

It's difficult to prescribe you the dosage without actually evaluating you. The medication, however, should be taken at bed time to minimise dizziness. For Dose advise you could contact your doctor again.