Certified GKH Gardening Expert
Given the climate in Mallorca, I would recommend planting trees in very early spring and that you use a heavy watering routine for them through the first summer after they are planted. This will provide them with enough time to become established before the heat and will help their tender roots thrive for the first summer.
Be sure to remove any fruit that may start to develop the first year. The trees should be spending their energy developing roots instead of fruit and you will have a better quality fruit and harvest in future years by letting them do this the first year.