You can start using your points at any time, you do not have to have a certain amount before being able to spend them.
When you place an order, you can only use 15% of your orders total with points. So say your order totals $100, you can only use $15 worth of points on that purchase.
To use points on a purchase you need to convert them into a gift card, which you can do in your account dashboard under Eden Points Program. You then use the gift card number to apply your points to your purchase.
Only one gift card can be used on an order and eden points can't be used to buy eden gift cards, due to the fact that eden gift cards don't have a limit of how much can be used on a purchase, unlike the Points Generated gift card.
Hope this helps & hope I still have it all right.