Got an offer, have questions about sick leaves.

Hi all, I just got an offer for specialty customer representative role. I want to know how flexible is FedEx about sick leaves. I probably undergo through an IVF in coming months and, before joining or accepting the offer I seriously need to know how and when I can use my sick leaves. I asked questions about it to recruiter, but didn’t get clear answers. Can somebody help me with this? I’m in Texas by the way.