Maybe
yes
This is different for everyone but mine started right away.
it really depents how far into the pregnancy you are....
Nipples will darken during pregnancy.
There is a good chance your nipples will hurt in the beginning, middle and/or final stages of pregnancy.
Yes; it is common to have sore nipples during the first trimester of your pregnancy.
Many women find their nipples and areolae (the dark bits) get larger and darker quite early in pregnancy.
Maybe
Yes, they can.
Mastitis or pregnancy
yes
They can be, but it can also be an early sign of pregnancy.
I had sore nipples (so bad that the shower water hurt) with each of my four pregnancies and have heard the same complaint from lots of women.
Your nipples become darker, fatigue, missed period....
It can be but, also it can mean a lot of other things.
Yes its normal, they are preparing themselves for breastfeeeding.