We recommend that you check your humidifier often until you become familiar with the environment. Dry climates require more attention than humid climates. It will also depend on your personal habits. If you open your humidor several times a day it will require refilling more often than if you open it once every week.
As a rule of thumb you should add distilled water to your humidifier about once a month and 50/50 solution every 2-3 months. Never use tap water.