If the garden has poor soils, applying compost helps in a number of ways. Apply it now for winter benefits. Compost tea doesn't compensate for the need for organic material in soils. Be sure to amend the soil well when preparing a new planting bed. Remember the reminder about planting trees.
Tree roots establish themselves better if they are planted into the native soil.
When you plant one tree, just remove the soil and plant. If the area drains poorly, do plant the tree on a slight berm, above grade, to enhance the drainage. If you do prepare an entire planting area, such as a new landscape, incorporate organic matter deeply and thoroughly throughout the whole space. When the spring growing season starts, the fall compost pile may have broken down sufficiently to brew some compost tea. In essence, compost tea results when fully composted materials are steeped in water.