Julie,
The size of the tree depends on you. We encourage people to keep their trees smaller by pruning. Which is a really easy thing to do. Or you can let it get taller and they could easily get 30 feet tall if you let it! It is also very easy to keep it at an 8 foot tree.
IF you follow our directions explicitly in 2 to 3 seasons. After planting you will get fruit. If you just stick it in the ground, it may take four or five years.