611.2e If a resolving spell or ability both puts a nontoken permanent onto the battlefield and creates a continuous effect stating that the permanent “is ,” that continuous effect applies simultaneously with the permanent entering the battlefield. This characteristic is usually a color or a creature type. If the continuous effect says the permanent “becomes ” or “gains ,” that effect applies after the permanent is on the battlefield.
Example: Arbiter of the Ideal puts an artifact, creature, or land card onto the battlefield and says, in part, “That permanent is an enchantment in addition to its other types.” An ability that triggers whenever an enchantment enters the battlefield would trigger. The permanent doesn’t enter the battlefield and then become an enchantment.