Pre seed and sex?

Sisilia • TTC#1, I have endometriosis.
How often did you had sex when you used pre seed? I am on my fertile window now and we usually have sex for 6-8 days in a row ( 4 days before ovulation, ovulation day and after ovulation)
This is my first cycle using pre seed and I was planning to do it on all days we are BD. Is there any harm?