Epic Capsules - Is loot allocated upon purchase or opening? How to game Star Guardian Skins.

So the age old question - the chests and capsules you receive, is the loot pre-determined as soon you as receive it or upon opening?

If

Case A: Then if I buy 5 epic capsules on Thursday, and Star Guardian skins drop Friday, they will have a 0% chance of "Dropping" for me

Case B: I buy 100 Epic Capsules (Theoretically), when new skins come out, I can just open a few and have a good % at getting them due to the guaranteed epic or higher rule on the epic capsules.

Anyone know or have a quote from A riot employee?

The reason why I ask is because it's been confirmed by RIOT that the chests/capsules have a stronger % to drop items you do not own (Yes I know, people still get duplicates....)