Birth control pill switch

Brianna
Hey girls so I was on orsythia first and was having trouble with my periods. So they switched me to orcella I started orcella on a Sunday like I thought I was supposed to when I had only taken 3 or 4 of my last pack of orsythia. Should my orcella be working? Or should I be using a backup method? And how long will it take for it to kick in? 
I appreciate any help I can get with this 
Thanks ☺️