H1B to Day1 CPT - how to explain to my employeR?

I am probably overthinking this but i want to make sure I get it right. Looking to do phD on Day 1 CPT program and need to ask my employer if they will let me switch from h1b to day 1 cpt. How do i approach this conversation? I am paranoid because they were so clueless about the H1B, PERM process etc, i had to guide them and I don't want them to say no based on lack of understanding.