(hope I'm not out of place posting here, but I used to post on here so I thought I would give my experience/advice)
The general wisdom I have heard is a year of not preventing. My OB tells people to get testing done/help after 6 cycles of actively trying. She never told me the reasoning, but here is what I think it is - 80% of couples will have conceived within 6 cycles. Of the remaining 20%, half of them will concieve in the next 6 months. The other half has infertility issues. Therefore, if you have not conceived in 6 months, there is a 50/50 chance you probably have an IF issue. In my opinion, better safe than sorry.
I did not wait a year to see an RE...and I'm glad I didn't. I could tell something wasn't right within a few months off the pill (wonky cycles, hot flashes, short periods, short luteal phase, etc.) and turns out I was right. I had DOR (dimminished ovarian reserve) due to being a fragile X premutation carrier. I am glad I did not wait because my condition (like some others) only gets worse the longer you go and it could have prevented me from conceiving at all.