Steve, reading this thread all over again, I remember Maso here in Canada, her lemon seedling fruited after about 12 years, but the cuttings that she rooted from the lower level branches of that fruiting seedling started flowering the second year. So when a seedling tree starts fruiting, it sends the signal all over the tree and any branch on that tree can be rooted or grafted on to some rootstock and bloom in 2-3 years.

Here are her posts:

https://www.gardenweb.com/discussions/2809545/help-lemon-tree-not-flowering

https://www.gardenweb.com/discussions/4027559/my-new-citrus-project

In the second post you can read that she took the cuttings from the low branches on her tree.