You give your credit scores as coming from TU and EQ. My guess therefore is that you are getting them from Credit Karma. I am a big fan of Karma -- it's a great tool for pulling your reports. But its scores are Vantage Scores, rather than FICO 8. Nothing wrong with tracking your V-scores, but you should perodically pull your FICO 8 scores too. We can suggest some extremely cheap ways of doing that (a few dollars per year).
I like your idea of steadily adding more cards over time. Have you thought about adding them not based on 0% offers but based on signup bonuses? The amount of money you are saving by having a 0% card is small. My guess is that its the equivalent of having 10k in a high interest (1%) savings account for an entire year. That's $100 (before taxes). You could make a lot more in tax-free money from CC bonus offers. You could use your tuition bills to meet the minimum spending requirements and make a ton of bonus money.
You are also clearly thinking about what looks good on your credit for the very long term -- what is going to look good 5 years from now or even further. Carrying CC balances every month (that's what you do with a 0% card) will look bad in the credit scoring models of the future. It's called being a revolver. That's contrasted with transactors, who are people who pay their cards in full each month. Transactors have been shown to be much less risky than revolvers, statistically. So many lenders moving forward will be analyzing your reports to see if you have been more of a revolver or a transactor -- not just that month but also month by month stretching back several years.
Incidentally if you want some extra scoring points in the run up to applying for a new card, you should have one card reporting a positive balance, all others reporting $0 and your total utilization < 8.99%. I don't know how your loans work, but if the lender establishes your interest rate partly on your scores, then that's one more reason to keep your CC balances low. You are getting new loans every year, right?
The good news is that you will be in great shape down the road as far as your credit scores You will never have missed a payment, you'll have a great Age of Oldest Account and Average Age of Accounts, and your cards will all be paid off. Sweet.
PS. There is one thing you are really well poised to help the folks here on the forum look into, and that is the effect of something called the SS loan technique on a person who only has student loans (especially if they are all in deferment). The technique (if it works for you) would give you an additional 30 points on your score. Let us know if you want more info on that.
