Hello, Welcome to HCM, I am Dr. Das
Look, first of all, your period has just occurred. that means you have not ovulated yet. so, there is no chance of becoming pregnant.
Secondly, you have started the pills. It prevents pregnancy
by stopping ovulation, by inhibiting fertilization and anchoring of the fertilized ovum in the uterus
So, you do not have to worry, just continue taking the pill as mentioned. It will be alright. Nothing will happen.
Hope this becomes helpful.