How does Notify When Back In Stock work?

Our notify when in stock system is a "first come first served" system.
Here is how it works:

1. If we enter 10 units of a product into inventory, just the 10 people who have been signed up to be notified for that product the longest will get notified first.
2. The system will then wait for 12 hours. After 12 hours is up, it will re-count how many of that product are left in inventory. If there are 5 left after 12 hours, the system will notify the next 5people who are signed up to be notified.
3. The system will continue to do step 2 until all the units are sold or everyone has been notified.

We chose to set up the system this way for a few reasons:

1. So that if you receive a notification email, you have a window of time to act.
2. So that if we make 10 units, but 80 people are signed up to be notified, not all 80 get notified at once.
3. Because if we notify everyone at once, then a lot of people would show up to the product page but find it sold out, so they would have to sign up to be notified a second time and essentially lose their place in line.