Wisteria can take 5 - 10 years to bloom, even if you are pruning as Mark suggested and it's planted in ideal conditions. Plus, too much pruning of a young Wisteria can result in cutting off the next years flower
buds. I prune mine in late July, early August just to get it under control and shaped the way I want it.
The following is information taken from the Michigan State University website:Considerable confusion exists about pruning wisteria. The
two species most commonly grown are Wisteria floribunda
(Japanese wisteria) and Wisteria sinensis (Chinese
wisteria), both of which bloom before or with the
unfolding of the leaves.
Pruning wisteria extensively during the dormant season may
encourage rampant vegetative growth the next spring.
Instead, in July prune out the long, straggly growth
except those branches needed for climbing. This is more
likely than anything else to induce flowering. Shoots
should be cut back one-third to one-half their length.
This will induce them to produce the short spurs that will
bear next season's flower clusters.
Wisterias are normally vines, but pruning can make them
take shrubby and/or weeping forms. Heading back young
shoots holds the height at a definite point and after
several years, the plant produces a trunk-like stem. Then
leaders can be allowed to droop to the ground.
Wisteria will bloom abundantly if planted in good garden
loam with full sun, watered well the first growing season
and pruned in the summer.