BCP to Prenatals?

Alex • Married to the love of my life and TTC #1!
Hi everyone!
​I'm on my first month off BCP and wondering when is the right time to start taking prenatal vitamins? DH and I and TTC Baby #1 next month and concentrating on getting healthier this month. 
​Also, will Prenatals help regulate my cycle? A little nervous about being irregular coming off BCP. 
​Thanks for your help and advice!