I Just Switched Birth Controls From Sprintec To Mercilon. I

I just switched birth controls from Sprintec to Mercilon. I waited to start Mercilon until the Sunday after my period (May 14). Can I have unprotected sex without worrying abiut pregnancy, or should I use a backup form of protection, such as condoms. If so, how long before I can have sex without using condoms? Thank you!