New dog owner seeking advice about: Bathroom break schedule

Hello everyone! A couple of months ago I adopted my first dog and I LOVE him. He's so sweet. Right now I'm on holiday break so I am able to take him out as often as needed, but next semester I will be finishing my associate's and will be quite busy. I'll be able to let him out before heading to class at about 8:30 but then I won't be getting home until about 10 or 10:30 pm. Obviously I'm going to hire a dog walker like I did this past semester, but I'm wondering if seven hours is too long to hold it? I'd be getting the walker to come at about 3:00 to walk him for 20 minutes and make sure he goes to the bathroom.
Little info about my Boy Buttons:
He's almost 2 years old
Weighs a little over 9 pounds.
He measures about 14 inches from neck to tail
He has a lot of energy that I try to burn with inside play and a long walk once a day, in addition to 5-10 minute bathroom breaks.
The person that I adopted him from told me he's a Maltipoo and he is neutered.
Somewhat crate trained. I don't keep him in the crate when I leave for school/work, I just keep him contained in the living room and make sure there's nothing out for him to get into.