The woman's conception month in the Chinese Baby Gender Prediction Chart is the Chinese lunar month. This Chinese Lunar Calendar tool can list the Chinese lunar months using western Gregorian calendar dates. This will help women to choose the conception month.
The Chinese lunar months might have one day off when comparing with different time zones. If you choose the date of the conception month in the middle of the lunar month, then you won't miss the lunar month.
To predict the Baby Gender is from Chinese Baby Gender Predictor page using your birthday and the pregnancy month.