Switching from combined pill to minipill birth control

Patient: My doctor recommended I switch from combined pill birth control to the minipill due to headaches. I just picked up my new pack of minipills and the instructions say that you are supposed to start on the first day of your period when switching (skipping your inactive pills). Unfortunately, I just finished the 7 inactive pills of my previous birth control pack and my period just ended. Is it okay for me to start them tomorrow? Will there be any strange side effects like having another period immediately?

Symptoms: None