When it turns into a creature, it is no longer an enchantment.

This card now uses the Reach keyword ability to enable the blocking of flying creatures. This works because a creature with flying can only be blocked by creatures with flying or reach.

The ability only triggers if the creature spell has flying, regardless of whether an effect would cause the creature to have flying once it entered the battlefield.

A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of his or her most recent turn. It doesn't matter how long the permanent has been a creature.