IB- how long did yours last?

JoElla
If you experienced IB before your positive, how long did it last?
 I've had a brownish pinkish discharge since two days ago, was due for AF today but still just a bit of the dishcharge, only when I wipe, being late isn't uncommon for me as my cycle is 28-3 days but I never have this sort of spotting before AF. I've had super super faint positives yesterday and today, but trying to not get my hopes up in case its chemical. 
Wondering what others experiences are. Thanks!