The ability is broken up into two parts:
- Creating the Draught through the ability (Action)
- Drinking as a potion, as normal (Action)
The rules for drinking potions are previously established and well-understood as an Action to consume/apply.
Normally, retrieving a stowed object can be done as a free interaction. Since you don't actually have to already have the Healing Draught in your pack, this ability creates it rather than just retrieving it.
You can make the Draught ahead of time.
Missing from your description (maybe using an older version of the Artificer or decided to exclude it):
If not used, the vial and its contents disappear after 1 hour. While the vial exists, you can't use this formula.
You can use the Healing Draught ability ahead of time, and it will be considered a stowed object until you use it. In this case, it has the following action economy.
- Retrieve stowed Healing Draught (Free Interaction 1/turn)
- Consume/apply Healing Draught (Action)
Your usage scenario is not optimal; you're right
The way you originally expected the ability to be used is definitely not ideal. In combat, you don't want to spend a turn creating this Healing Draught just to spend the next turn actually using it. The speed at which you achieve this healing is worse than another class simply casting Cure Wounds.
So, it should be clear that this ability was not intended for use during combat in the above way, losing two turns of tempo to heal instead of ending the fight. It should instead be used before a major fight in which the party is expecting the preparations to be necessary. For example, right before encroaching on a dragon's lair, manifest the Healing Draught and store it on your belt or in your pack.
Or right before encroaching, give it to a friend, which is a major advantage of the Draught that other classes can't replicate. – Erik