Start taking them as soon as you can. Sooner the better.
I take the flinstone vitamins that are chewables. The bottle says complete on it. 2 a day. I got the bottle from Walmart for 5 dollars.
Wal-Mart has prenatals there. Many women don't find out that they are pregnant til 2 or so months in. Don't stress just take them as soon as possible. Good luck hon.