How can I change Potion delay?

Whenever a hero uses a potion of healing or mana, a certain amount of time must pass before he can use another potion. Is there anyway to change this delay?

Yes. You would change it under the ability of the item that is being cast.

So you would go under the object editor, then the ability tab. Find the Items folder (Should be in there somewhere, if it's not on the main list, try neutral passive) and then find your ability. The cooldown is in there.

If you want to make certain potions affect only certain other potions, change the cooldown group (In the Item tab, under the item itself, not it's ability).

Hope that answers your question, and good luck with your map. :D