I had one early loss while on the pill, and had breakthrough implantation spotting with that. It was 2-4 days before I was supposed to stop the pill and have the "week off" for AF. (But, AF did come, super heavy and painful.
With my first DS (a total surprise), I had plain, bright red spotting - that is, enough to wipe once or twice but not more (just as with the early loss) - around when I figured AF was due (I was also not keeping more than loose track of AF). I figured AF was on the way, but she never showed and I had no more spotting. It was about 3 weeks later that I finally considered that missing AF and super-duper nausea and fatigue might mean something!
With #2 (more expected), I had a super faint BFP at 9dpo, and the same sort of very light, but red spotting 2-3 days later.
With #3, no spotting AFAIK.
TMI on this one - With #4 (this one), I had a really weird, short LP the month prior. I knew that if that happened again, AF was on the way. Sure enough, about 9dpo I started with brownish spotting and discharge, assumed it was AF, and preemptively used a menstrual cup. Two days later, I found that my "just for the fun of it" HPTs were positive (I thought it was evaps), and more were positive that day, and while there was a variety of discharge in the cup, it was still more brown than red. I don't think I really had any more of the brownish discharge after that, though, but it may have been up to two days of it.