Generally, a couple should see a specialist if they have been trying for pregnancy for more than one year.
If a woman is 35 years or above the consultation should be after 6 months of trying for pregnancy. In case women has very painful periods, delayed periods, has undergone pelvic surgery, history of pelvic inflammatory disease, family history of early menopause or primary ovarian insufficiency, consultation should be earlier.
Similarly for male partners who have prior health problems that decrease the sperm count and motility and thus decrease the chance of fertility. These couple should seek evaluation sooner.
After consultation they need to be proactive and get the appropriate treatment.