Notice to Vacate Requirements in Henderson Nevada?

We were served a written notice by our landlord to vacate the property on 3-8-2010. No reason or complaint was made by the owner or in the notice. The notice states that we need to be moved, the home cleaned, and the keys returned by March 20 at 5pm. Owner is trying to short sell the home, and believes that having it vacant will help it sell. Two days after she served this notice, she filed and served us a 3 day notice. i have found a few articles that say she must first wait until the date on her notice to vacate before she can go to the next step and file a 3-day notice with the court. Can anyone give me help on this one?? Thank you so much for your time and istance!