We’ve had a similar situation: husband has spina bifida. For the first baby, I took high-dose folic acid and started trying immediately. I don’t think you need to wait 3 months for levels of FA to be right. For the second, I was pregnant before I started the high dose FA. Happily, both healthy boys. Neither of us were current smokers. Also I think that a lot of foods are fortified with FA. I’d just make sure you were taking a high dose and get on with it! Good luck.