If you want to delay the display of this task in the agenda, use ‘SCHEDULED: <2004-12-25 Sat -2d>’: the task is still scheduled on the 25th but will appear two days later. In case the task contains a repeater, the delay is considered to affect all occurrences; if you want the delay to only affect the first scheduled occurrence of the task, use ‘--2d’ instead. See org-scheduled-delay-days and org-agenda-skip-scheduled-delay-if-deadline for details on how to control this globally or per agenda.
I noticed that beorg has the show up feature, maybe it's the same feature ? The '-2d' is supported by emacs already.
Thank you for highlighting this. beorg doesn't currently explicitly support this. I will look at adding this for a future release.