Sony announced on the 8.9.2014 that if you have yourself Pre-Ordered Destiny that you can now Pre-Load it onto your Play-station system(s).
They have also notified that destiny can be Pre-Loaded onto your console in one of two ways. The owner of the Play-station console can enable "Auto-Download". What this is, Let's say your pre-ordered a game and it's released on Christmas, The game would automatically download on Christmas day only if you have "Auto_Download" enabled. What if it does not download? You're getting inpatient? That's okay, Don't state that you can Manually download it. It works both ways. This can be accomplished by going to Destiny on the Play-station Store page and shitting the "download button".
The PS4 version of the game is listed as a 17.4GB download, on Destiny’s Playstation Store page. Those numbers have always been accurate in the past, as was the case with Diablo III: Reaper of Souls – Ultimate Evil Edition for the PS4, but will probably be marginally accurate.