It's possible to...?

Know which avatar skins are gonna be released before it appears on the orb shop. I noticed some games you even know the exact date for skin and their aspect even a month before it appear on shop.

 

nope.
the list may change daily at midnight (japan time). you can expect seasonal avatars within their season, but there is no way of knowing if it will be old or new ones.
each box set appears at least once a year, but the order seems to change every time.
new avatars are more likely to release and are avilable for a longer time period, but it takes a while until they return.
old avatars sometimes are made available for 1 day only, but usually with some kind of discount.