Headband of Vast Intelligence

This intricate gold headband is decorated with several small blue and deep purple gemstones.

The headband grants the wearer an enhancement bonus to Intelligence of +2, +4, or +6. Treat this as a temporary ability bonus for the first 24 hours the headband is worn. A headband of vast intelligence has one skill associated with it per +2 bonus it grants. After being worn for 24 hours, the headband grants a number of skill ranks in those skills equal to the wearer’s total Hit Dice. These ranks do not stack with the ranks a creature already possesses. These skills are chosen when the headband is created. If no skill is listed, the headband is assumed to grant skill ranks in randomly determined Knowledge skills.

Craft Wondrous Item, fox’s cunning; Cost 2,000 gp (+2), 8,000 gp (+4), 18,000 gp (+6)

If I wear a headband of vast intelligence, do I get retroactive skill ranks for my Int increase in addition to the skill ranks associated with the item?

No. The skill associated with the magic item represents the “retroactive” skill ranks you’d get from the item increasing your Intelligence. You don’t get the item’s built-in skill ranks and another set to assign however you want.