ive taken scions before, and forgot to graft them...I left them in a plastic bag, in my greenhouse.
the scions Eugenia pyriformis, leafed out, and stayed alive for months, before finally dying.
Scions can remain viable for a long time if properly cared for.
I've grafted some other scions that I wrapped in buddy tape, and let sit around the house for a week, on the table, before finally grafting them...they did fine.
just felt like adding some notes about my experiences.