You're welcome. I actually have my first key lime growing right now. It's about a month and a half old, and is just under 2 inches tall w/3 true leaves. Meanwhile, I have a grapefruit seedling that is around 2 1/2 months and is around 3 1/2 inches tall w/8 true leaves. I've never tried growing a pummelo, so I'm not sure how vigorous they are.
Good luck!