Really quickly, they should be outside. If your weather is especially hot, some mid-day protection may be advisable. Ideally it should be potted in a fairly gritty free draining soil mix. If not be very careful to ensure that the soil is not kept constantly wet. When watering, water thoroughly then wait until the soil approaches dryness before repeating. Frequent, shallow watering is the wrong approach.

As long as you are seeing growth a younger tree, still in the early stages of development, can be fertilized regularly throughout the summer. A balanced (10-10-10 or 20-20-20) water soluble fertilizer mixed according to directions about every two weeks will be fine.

If your weather is damp be on the lookout for small dark spots on juvenile foliage, this is black spot fungus and must be treated quickly.

Unless you have purchased older, well established specimens there won't be a lot to do right now other than your daily routine. Just take some time and learn how to manage them properly.