This is a little non-direct, but the OP did ask what some parents did. My main point is at the bottom, so bare with me.
As most kids in high school, mine wanted to get jobs when they were in high school. I only allowed this in the summer. I didn't allow my kids to have jobs during the school year. My theory was: "School is your job". I knew that if they busted their butt in school (Their Job), that it would pay off big time at the end. I.e. scholarships. If the kids needed/wanted anything during the year that their christmas, birthday, allowance money couldn't provide; I would pay for it. (If it was legit). If I didn't agree, then they could wait for their next birthday or christmas.
Well, my theory was right. It cost me NOTHING for my kids to go to college. And both had many choices on where to go. My daughter went to the state university and my son went to the air force academy. I continued this policy in college. So my daughter could concentrate on her education, and it wasn't costing me anything to go to school, we gave her money (Allowance) each month for spending. She later liked living in the dorm so much, that she got a job as a Resident Advisor which gave her free dorm and free food. Plus it paid her a little money each month. She finished her B.A. in 4 years.
With my son at the academy, we felt the exact same way. He busted his butt in high school, got multiple scholarship offers, and it cost us NOTHING for him to go to college. So, like his sister, we gave him money (Allowance). Gave him a check twice a year. He used this money for ski lift tickets, food, entertainment, etc... Whatever he wanted for.
As such, he was able to basically save a lot of money by the time he graduated. Between his cadet pay and the money we gave him, he graduated with more than enough money to set up an apartment, furniture, etc... We also, as part of his graduation present, the car we let him use at the academy for the 2 years he could have one, we signed the title over to him. So, he had no bills. No debt. Plenty of money in the bank. So, he took out the $35,000 USAA 0.5% interest loan, and invested it. $5,000 in CD's; $5,000 in a Roth IRA, and again for the next 2 years. The remaining $10-$15K stays in the bank. Each year, he'll take $5,000 and add to his Roth IRA with it. So, when his 5 year loan payback is over, his $500+ monthly payback with be over with. THAT will be like getting a Pay-Raise. That's $6,000+ PER YEAR. $5,000 of that will be his yearly IRA contributions. He keeps the extra $80-$90 a month. He's never seen it anyway, so he'll never miss it. Plus, during those 5 years, he will have received 2 promotions. To 1st LT and to Capt. If he does $5,000 per year until he's 62, at a small interest rate of 4% per year, he'll have approximately $500,000 in a ROTH IRA. TAX FREE. This doesn't include military retirement, career after leaving the military, etc...
In other words, while starting sooner is better, if you plan better DURING the 4 years at the academy, you can use the low interest loan from the USAA for investments and long term, instead of using it for a car or setting up an apartment when you graduate.