It is always good to water your newly planted tree for first 30 days, but once you cut back to a normal 2 times a week watering regimen your new tree is not completely home free.
It takes approximately one year for your freshly planted tree and root system to get acclimated to its new surroundings and soil. So, in that time frame, please be sure to give its necessary TLC (i.e. water and fertilizer)