It is usually recommended to start taking a vitamin supplement at least 3 months before trying to conceive. The most important vitamin to take during pregnancy is folic acid, which is typically found in multivitamins at a dose of 0.4 to 1 mg per tablet. Taking a separate folic acid supplement at this dose is also an option. Your pharmacist can help prescribe this supplementation, and some insurances may cover it. It is best to consult with your pharmacist to determine the best product for your needs and preferences. Some individuals may require a higher dose of folic acid, such as 5mg per day, and your pharmacist can provide guidance on this.