What regulation states that I can receive promotion points for my degree?

Look at the point tabulation for the promotion package. It's if you have the degree, not when you got it. Also, your soldier skills are worth more points for a SGT promotion than for a SSG promotion. Both max points at 800, but they are allocated differently. You get more promotion points for the same fitness score for SGT than you do for SSG, but you get more promotion points for that degree for SSG than you do SGT.

Now... timing wise, as an NCO you wont be able to use your current degree as a "bullet" point on a future evaluation for professional development, because you didn't achieve it during the rating period.

There are promotion point calculators floating out there. Find one, and you can specifically see how to game each promotion point.

One thing I learned in the civilian sector in finance calculating out the pay bonuses for sales staff was WOW it's easy to move numbers by managers changing the slightest parameters that impacts the bottom line pay check.

Here's what I'm getting at. Dollars to doughnuts weapons qual is your most powerful promotion point return for he given amount of effort to achieve those points. ACFT as well I suppose if you are a fitness nut. But education stays with you and you carry the accomplishment forward without having to redo it. Whereas ACFT and weapons are something you have to keep on top of and it can go up or down.

SPC (Join to see) Congratulations on acquiring your degree... best of luck in your Military Career.

There is a regulation that covers everything about enlisted promotions (and reductions).
AR 600-8-19.
For E4 to E5, civilian education is worth a possible max of 75 points.