Question about Amazon Pre-order Price Guarantee

[Wolfking]

Ok, this may be stupid, but I need to know, cause I have a method of pre-ordering, and I'm wondering if it's a bad method, and actually losing me money, but to get to the bottom of it, I must ask this question. Why you pre order something, do you get the Pre-order Price Guarantee from when it was introduced to the site, or only since when you place the order?

Like for example, let's say a movie up for pre-order was made available on August 26, 2014. but the release date is for January 12, 2015, if I ordered let's say on January 5th, and they has been a price drop on October, would I get October's price drop, or not?

Cause, I like to pre-order a week before I make a purchase (except for limited editions), because I need to figure out, how much I can spend and not run out of funds. So am I doing it ok, so should I just pre-order everything I want the second it goes live?