How long could I leave my freshly stretched (one week) septum piercing vacant?

I don't have a septum piercing, but I did have stretched lobes. If you take it out it will shrink, probably smaller than a 12g (that's what happened with my ears when i'd stretch) but at the same time, there's hardly a difference between a 12g and a 10g so I wouldn't worry too much. I know you probably don't have time, but bodyartforms.com has a large selection of jewelry you could use as a retainer in the future.