We have a similar law here (6 mos). I think it is a good idea to limit distractions for new drivers, but a year seems too long. We did expect our kids to follow it (many people around here don't care), but I'm sure they probably didn't at times. It helped that we were in a pandemic for most of that time, so nobody was riding in cars together anyway.
All that said. I think it depends on your DD. Is she one that can learn from a small punishment? I have one that one time being called out and missing a day would be enough that he would follow it from then on. Then I have one that would probably do it again the next day. That one would probably start with a week.
I don't think there is a right answer. A single day with a talk about why that law is there and stressing that you expect it to be followed, along with warnings that repeat offenses will mean longer consequences... seems adequate.
Mama to three boys ('03, '05, '07)