First-Time Streching My Ear Piercing?

Hey, I'm Maggie. I've been wanting to gauge my ears for about 3 years now, and I've done my fair share of research. Although i'm excited to get to the stretching, i'm not really sure what size my ear piercings are at right now. If it matters, I got my ears pierced at pagodas in the mall. I was also wondering if I do end up gauging them (If you can't tell I'm a bit nervous =P) Will they effect my second ear hole piercing? I have a pretty average pain tolerance but how badly should I expect it to hurt? Thanks for all the help in advance. :]