Cd21 progesterone level blood tests question!

Katrina • I am ready for this journey and to bring life into this world with the man I love ❤️

I am currently on cd18 and 1dpo and I am suppose to get my cd21 blood test done this Thursday to confirm ovulation. My question is that I’ve read online that you are suppose to get the blood test done 7dpo for accurate results. The day I am suppose to get it done I will only be 4dpo. What are your thoughts on this? It will be very helpful!