I think it is good to take now? I read your other post about when you were gonna start.
You can buy straight folic acid (800 mcg is the recommended dosage for pre-natal / pregnancy), or you can buy a pre-natal vitamin which is like a multi-vitamin including the folic acid. If you decide to take a regular multi-vitamin in conjuction with straight folic acid, make sure you check how much vitamin A is in your multi-vitamin, because too much of this can cause problems too.
I looked up pre-natal vitamins online to find the recommended dosages.