Getting my braces out. Retainer help!

Hi
I am set to get my braces removed in a couple of days.
My dentist says that I will have to wear retainers which I am ok with.
But I then asked him how long would I have to wear them.
He just told me around six months. But he also added that it varies with people and the movement of their teeth.
He didn’t really add anything onto that.
Do I have to wear them 24/7? Because I’ve had my braces for a long time and I just want to be free (at least during the day) of those metal things.
Or can I only wear them at night until my teeth settle in place?
Or what if I went to school and then put them on when I got home? (3:30pm-8:00am, so around 17 hours?)
I’m not sure about this stuff so hopefully you can help. (: