I got my left lobe pierced at 6g, no stretch. It kinda self stretched after the healing period to 4g and I've left it there and waiting for it to be ready to stretch.
My right lobe I got pierced at 6g and stretched straight to 4g, I think 1mm or thereabouts in the initial stretch is probably okay. I didn't really get any additional advice from my piercer about how much more was safe as i just wanted my right to match my left in size but I'd say one size or gauge is a good benchmark to work with.
I've had no real troubles but I'd say, based on my experience so far, expect to wait the full 8 weeks of the suggested healing time for a lobe, maybe even a bit more, as the hole is much larger than getting pierced at 14g for example and so logically takes longer to heal.
So in the end, see if you can find someone who will pierce you at a larger guage than 10g before the stretch. I think 6g might be the biggest needle available but not really sure on that...otherwise I guess she would have just pierced me with an 4g needle?
Pierced, Punched, Stretched & Scalpelled
IAM: MrMeaner