It helps to be a high-performer in your metrics, a "Million Dollar" sales associate and/or someone widely recognized for performance in sales, PAs, recaps and credit. Then you could manipulate and leverage your SGM and ASM into giving you time off, regardless of blackout dates. If they don't budge then they lose you and the store takes a dive in metrics.
We all know what happens when metrics go south, so your manager will happily oblige. Otherwise, they will get a typical high school student or someone trying to milk unemployment benefits to replace you, people who aren't as skilled or could care less about what their numbers are. After months of plummeting metrics, the DM will be on the manager's case and soon their jobs are on the line because no amount of coaching or PIPs are going to fix the ineffectiveness of the sales associates who replaced you and the other top performers.
The "we can't find good salespeople to make the numbers" line isn't a valid excuse to give the DM's and regional managers when they confront your managers about metrics. Take it from me, a former hardlines ASM.
So, unless your manager is clinically insane, they will do anything to keep you if you are good. You have more leverage than you think, especially if your peers aren't performing as well.
The advice by @cpb is certainly good to heed, too, but if you just need to milk a few weeks or months more out of the job and you are a high performer, why not?