This is a very common question for those interested in fruit trees.  People that want to take the time to plant and care for the trees want to know how soon they can be rewarded by the fruit that the trees will bear.  The answers to these questions will depend on the variety that you are trying to grow.

Generally speaking, a fruit tree is able to bear fruit when it can blossom on its own.  It takes several years for this to happen.  The environment can effect the amount of time that it takes to bear fruit.  Factors such as age, growing conditions, and cold or chill hours all will determine the time frame for fruit production.  Also, dwarf trees will often produce fruit 1 to 3 years sooner then the full size version of the tree.

The University of Connecticut listed the time frame for a variety of trees.  According to their website, an apple tree will produce fruit in 2 to 5 years after a planting a 1 to 2 year transplant (or 3 to 7 years from being planted from a seed).  A sour cherry tree should produce fruit in 3 to 5 years (again assuming the seedling is 1 to 2 years old) and a sweet cherry tree will take 5 to 7 years to produce fruit (from a seedling 1 to 2 years old).  For the complete chart check out the website at http://www.hort.uconn.edu/IPM/homegrnd/htms/53ftbr.htm.