How long light/brown discharges in your first trimester should last?

I don't drink, don't smoke, and drug free... I think I am pregnant, just because of some symptoms i have for a week now... i started having light/brown discharges, not a lot, it doesn't make my day pad full nor a half... but was wondering how long usualy those discharges last? I have read that some woman experience in different ways.. but what's normal? I havn't taken my pregnancy test, it's too early... Thank you

P.S. - I had darker brown discharges for 1 day and a half, and today lights brown...