When can I change a nose piercing?

Alex

I got my nose pierced about three or four years ago and kept it pierced for two years after getting it .. it's been closed up for about 1 to 2 years now and I want to get it redone! I'm taking a new job, however, and I'm not sure if I'll be allowed to have it pierced. I end up getting it redone how long before I can change it to a clear one?