1 day spotting on Femara/Letrozole


I was due to start my period on the 9th. It was 2 days late. Yesterday evening I had blood when I wiped. I used a tampon and went to swim class. After class I took the tampon out and there was just a little brown blood on it. I threw a pad on and went to bed. Now today which is suppose to be day 2 of my cycle there is nothing. I am supposed to start my second round of Letrozole cycle day 3. Do I take it even if my period was 1 day of spotting? Should mention when AF was late I took a hpt and it was negative. Anyone have this happen? Did you continue with your next round?