TTC and fertility specialist

I’m 36 and my husband is 43. We always wanted 4 kids but not in the cards for us... yet (I remain hopeful though). We have been TTC #1. Since we have been unable to do this on our own thus far my family doc has referred us to a reproductive endocrinologist (fertility specialist) for further assessment. I’m not sure what to expect. What have others experiences been like? For those of you who need to see a fertility specialist, what are some questions you wished you asked early on in the process? Any advice/info would be appreciated.