You need to be at least 15 1/2. We do not a have a learner’s permit in New Hampshire, but you must have a copy of your birth certificate or passport for proof of age with you. You must have someone over the age of 25 in the front seat with a valid drivers license. You can have passengers in the car as long as you do not have more people than you have seat belts. You cannot drive out of state, or between the hours of 1-4 AM. For official rules, RSA 263:25.
You will need to perform at least 40 hrs of practicing before you are allowed to go for your license if you are under 18. At least ten of those hours must be night driving. Here is the official log sheet from the state if you would like to print one. You can also keep track on your phone or on a separate piece of paper and then transfer the information later onto the official sheet.
I cannot stress enough how important it is to practice driving. Like any other task you will perform in life, the more you do it, the better you will be. I recommend starting off in a parking lot or on very quiet roads, and then progressing to busier areas as confidence and skills grow. The last thing you want is to try something too hard and have a negative experience. You want to build skills slowly and surely and have driving be a positive experience for both student and parent. If you want to wait to try more difficult skills until you have learned about them and had a chance to master them in class, that is fine. As soon as class begins, however, you will really need to practice often. If you can start before class, you might feel more comfortable the first time you go out in the Prius, but everyone is different. Hang in there, you can do it! (Yes, I mean both student and parent!)
Here are some useful links to websites about best practices: