It is not an uncommon though around the mid-thirties for women to begin wondering when menopause will start. Women will begin to feel mild symptoms in their thirties and their first thought is usually that they are starting to go through menopause.
The first stage of menopause is called peri-menopause and can begin as early as the late twenties. Around the mid to late twenties the ovaries are already beginning to reduce egg production, although at this time no symptoms are usually felt. From about the mid-thirties to late thirties peri-menopause comes into full swing. Women usually only feel mild symptoms of menopause in during these years, but some can have very severe symptoms when it begins.
Full menopause usually starts around the mid-forties and symptoms will be very prominent at this time. Some women actually report not feeling much of anything, but that is rare. A good gauge how you will feel during your menopause years is how your mother and grandmother felt during their change of life.