I started with symptoms at 41,im not 46,the only real symptoms i had at 41 was only had my period about twice a year.The hot flashes have just started this last summer.
You CAN follow the same cycle as your mother or grandmother,however,my mother had her last period at 56 and my grandmother gave birth to my mom at 45,so there goes that theory for me.
I also heard it can last 10 years,im sure its different for everyone though.Good luck,we all need it.