In most areas, early spring, when the plants begin to emerge from dormancy, is the ideal time to set out any deciduous plant, including fruits. The surge of energy that results in new growth is matched below-ground, as new roots stretch out in every direction. If you wait until later in spring, look for plants grown in containers; they transplant more easily than bare-root plants after they have emerged from dormancy.
In mild-winter regions, late fall is a good time to plant fruit trees and berries. Cooler temperatures through the winter allow the plants to become established before the stressful heat of summer sets in. Most fruit trees begin bearing 2-5 years after planting, but you can expect a good raspberry crop a year after planting.