My obgyn also said for me to take extra folic acid. It is good for the baby's brain development which is crucial in the first trimester!
I'm 36 yrs old my OB told me to take my prenatal plus 800mg of folic acid daily. I started them before I got pregnant too and now I'm due any time now. I will continue them after my son is born as I will be breastfeeding..
Just take recommended dose on bottle. Don't take more than that, you can over do it. Just eat healthy - lots of veggies and fruit, lean protein, and whole grain carbs. Cut junk way back or out entirely. Go easy on soda and other caffeine. If you eat well your body will be getting all the nutrition you need to grow healthy baby. Congratulations!