Fruit tree age?

I am very much a novice in growing fruit trees, so if this is a stupid question, I apologise in advance.
I keep seeing advice not to let trees produce fruit until they're a certain age. This is not consistent site to site and varoety to variety, but some state 3 years, and some up to 7. How do you know when an individual tree is "old enough"?
I'm guessing that all my "first year in the ground" trees should have the baby fruit removed, but what about next year? They are all different types and sizes, so I don't have a clue what to do with them. They are locally bought, but the sellers didn't know much about them :(
Any advice much appreciated.
margo, wondering how they all followed her home...

I remove blossoms or fruit the first year. After that, I only remove fruit if the tree seems to be stressed. That is, if the leaves are brown and dropping. the fruit is small and dry, etc.

Since the trees followed you home they will probably give you pretty clear signs of the kind of care they need.

And, it is not a stupid question. It is often hard to remove the fruit that first year but the tree will thank you for it.

By the way, I also cut about one-third of the growth off a tree when I plant it to give the roots less to take care of while they reestablish themselves.

Yep. A tough question. Some people believe you should let those few apples grow so you get to learn A) what bugs are in your area and B) to get some reward for your patience. Others say that the tree, especially the modern grafted varieties, will really be stunted if allowed to fruit before the plant has grown the proper scaffold structure and plants to support fruitset.

A topic last week:
http://davesgarden.com/community/forums/t/828521/

Which brings up the point that these early years should be used to prune the tree and develop the proper structure from the beginning.

I was one of the opinions to leave them on, because they drop off 95+% of the time anyway based on my experience and if they stay the tree must really want them. One thing you do need to watch for however is if the limb is small it may bend down too much from the weight and that is not good if it is to be a main structural limb. So if it goes below vertical its time to pull the fruit off or tie it up. I had that happen once on my 150 apple trees.

Scot

Thank you all! great info :)

So, it really isn't the actual _age_ of the tree, but more how long it's been in it's new home? Makes sense.

katiebear, I know I should be pruning before I plant, but I really have a hard time chopping off baby leaves and flowers. "Wimp" really covers it :(. Next year I'll prune them, but before they start to wake up. I'm getting better tho, I actually pruned three trees this spring.

I'll keep watching all the threads, and maybe the trees will benefit :)

margo