Wanting to buy a new MBA for university work and figured I'd wait for the next promotion/sale/etc. Any idea when's the next big sale (historically)? TIA!
People don't go back to school in the spring, hence no spring promotion.
The only two Apple promotions that Apple has followed here in the USA are really the fall back to school one (August usually) and the Black Friday (day after Thanksgiving) event. Both now feature gift cards rather than cash back discounts.
Note that Apple's own discounts are very modest relative to other retailers, historically between 7-10%.
If you are looking for a deeper discount, it is advisable to focus your attention to third-party retailers. The MacRumors front page frequently posts articles when discounted products are available.