I believe you can get your vehicle inspected 3 months before expiration. I used to get my car with Feb expiration stickers inspected this week since I was always off work, and my work schedule in Feb was usually very hectic.

I also bought my wife a car where the inspection and tag renewal were off by 3 months and my mechanic moved my inspection sticker out a month for 3 years until they were aligned.

I don’t see how a police officer could do anything to you should you get pulled over since they would have no way of knowing your vehicle inspection stickers were now on a different expiration month.