Birth Control Implant

Kristin
Hello! I have just recently gotten the Nexplanon implant in my arm at the beginning of the month and haven't had my period yet. (It's been five days since it's estimated start date.) I had sex a week after I had it put in but I'm pretty positive I wouldn't be pregnant. I know the experience is different for everybody and I'm wondering if I should be concerned over it or not. I plan on calling my doctor if it doesn't start at all. What is everybody else's experience with the birth control implant?