TTC after birth control

Got off nexplanon 8 months ago and was on it for almost 3 years. Before that I was on the depo shot for 2 years. I'm now TTC and have been for about 4 months. How long should I wait before going to see a fertility doctor? How long does it usually take to get pregnant after getting off birth control? My period is suppose to come on the 12th of this month. It's been 5 or 6 days since ovulation and I'm feeling extremely nauseous and have a head ache but I may just be over thinking but I just feel different? Has any one else felt symptoms this early?