When the calendar turns to August, there are many things to do to get ready for the new school year. One of the many things to do is to get your kids (and possibly yourself) back on the "school schedule". For most families, this means waking up earlier and going to bed earlier. This causes some stress around most households. I know part of it in our house is the "summer is over?!" feeling.
How is the best way to do it? Part of the answer to that question is based on the fact that most folks take about a week or two to get settled in to a new schedule. Some families do not change their schedule at all until the first day of school. I think that guarantees that for the first days of school your child will be tired. And it will take a few days or more to get settled into the new schedule.
A better way to do it is to take 10-14 days and gradually get up earlier and go to bed earlier. It will be not so jolting for your family if you do it in 15-20 minute increments. Also, sleep specialists will tell us that the most important part is to wake up a little bit earlier each day. If you plan "well, I will just go to bed a little earlier" but you do not get up any earlier, you will not be tired enough each night to fall asleep soon after going to bed.
So if your 14 year old is sleeping until 11 a.m. but will need to get up at 6:30 a.m. (that is what is happening in my house), note that the difference is 4 1/2 hours between when they are getting up and when they need to get up for school. If you divide that into 20 minute segments, that comes out to about 14. So if 14 days before school starts, you get up 20 minutes sooner each day and go to bed each day 20 minutes earlier, you will end up on schedule when the school year starts. Note that this means maintaining this through the weekends.
Getting your child back on to a good sleep schedule for school will help your child get off to good start for the school year. Good luck!