A laptop is the one school purchase you'll touch every day for the next three to four years, so the goal is to buy once and buy right. Spec it for the work you'll actually do in year two, not just the paper due next week. If you can, get something with a recent processor and enough RAM to grow into — 16GB is the comfortable floor now, even if it feels like overkill today.
Here's the trick most people miss: the previous generation model is usually the smarter buy. Laptop makers push a new cycle every fall, and once a refresh lands, last year's version drops in price while doing 90% of the same work. Back-to-school in August and Black Friday in late November are the two windows when that discount shows up most reliably on last year's hardware.
The 0% intro APR window is a deadline, not free money. If a balance is still on the card when month 16 hits, interest starts accruing on whatever's left at the card's standard rate, and it gets billed retroactively to the original purchase date in some cases. Pay it off in full by month 15 and the math works out exactly like the $106.67 plan above.