A sudden change from being constantly with family to being alone all day can be hard. So set aside a bit of time in the weeks leading up to the start of school to have your dog practice being alone in the house while people are gone. The times don't need to be long, and you can leave your dog with a special treat, food dispensing toy, white noise or calm music as we do want the separation to be as pleasant as possible.
If Labor Day weekend is a busy weekend get together for your family as you say goodbye to summer, then try planning an afternoon nap for your dog either while people are out of the house or in a quiet room if people are going to be in and out. Then include your dog in the rest of the days activities. The flexibility to know that sometimes they get to be in the thick of things and sometimes they don't and both are okay will help your dog adjust to being alone on Tuesday.
Where will your dog stay?
When will potty breaks be?
How long a dog can be left alone varies from dog to dog and by age, with younger puppies and seniors often needing more frequent potty breaks. It's a good idea to consider the new daily schedule in terms of when will the last outing be in the morning? Who will be home first? What if they need to stay late at work or remain at school for an extracurricular activity - what is the back up plan? Should you arrange for a dog walker, friend or family member to come by on certain days? If so, it's best to get that in place well in advance and allow your dog to get to know them if they don't already.
Will your morning routine change?
Most dogs rest better if they've had some physical and mental exercise, so it may be a good idea to plan for that before everyone heads out for the day. If so, it's a good idea to take that new routine for a test run before the first day of school so that you know its doable for those involved when you have some extra time if things don't go as planned.
The end of the day is when we humans often want to unwind, relax, and spend time snuggling with our dogs. Which is wonderful - if that is how our dogs feel. If you've got a young dog, or a dog with a lot of energy, they may be raring to go just as you are winding down. Relaxing will go better if you first give your dog some physical and mental exercise, and then settle together.