Immersing the pot is perfectly acceptable, the water should cover the soil line. But, be sure not to over water your tree. Use a toothpick or a chop stick and stick it into the soil, if the pick or stick come out with soil on them, it's not time to water. If they are clean, time to water.
Another way to water is to use a watering can with a rosette but, the immersion method is by far the best method as far as I am concerned.