Sugar Coating NFP
A note to couples discerning using NFP. You are likely being mislead by whoever is instructing you. Almost all methods and all instructors we have ever worked with paint an incredibly rosy picture of '7-10' days of abstinence a month. This is outrageously misleading. If your wife has anything other than medical textbook cycles, you may have to wait MUCH longer.
Our average after using various methods over five years is closer to 18 to 20 days of abstinence just waiting for ovulation. Over a month is by no means irregular. Then you have five additional days of waiting. Then you have life interruptions/exhaustion from raising kids/menstruation. You will quickly realize why only 3% Catholic couples even try.
Know what you are getting into in advance. This method of spacing children can be extremely frustrating. AND you are also likely to get judgement if you complain. Not to mention endless unhelpful variations of 'have you tried....'.