Since when am I protected from pregnancy if I started using Slinda before menstruation?

Hello I started to take the first pack of contraceptive pills slinda before the period, because I was delayed 8 days, the pregnancy test came out negative. Am I.protecting now or only from the second blister? During taking the first package with the 12th tablet I got spotting lasted 8 days with placebo tablets there was nothing at all, I am now taking the second blister and also with the 13th tablet there was a very slight spotting. Am I protected from the second package or not yet