I had sore nipples when I ovulated but they faded some (this is normal for me, pregnant or not). They just recently got sore again (5 weeks). They were way more sensitive with my first pregnancy. I also did not have sore boobs this time. I have moments where I get a sharp pain or a dull ache but it's not constant.
I had symptoms at implantation so I knew immediately: I had cramping, stretching, and fatigue (3 almost 4 weeks). I don't remember having that with my first.