As long as you take your birth control within the allowed timeframe then your protection will not be affected. This information can be found in your pamphlet, but for Slinda it should be 24 hours. So not just blindly trust my words though, make sure to read your pamphlet to double check.
If you use it correctly you will be protected in terms of pregnancy. Make sure to both get tested for STI/STD before dropping the condom, even when you’re each other’s first.