Quick question? At what point should an early demo of a game be released to the general public?

On the game I am working on right now, with a bit more fixing up it will have some playability to it.

Of all the classes only two have skills, but I am working on skills for the 3rd class. Which will be a total of about 60 skills.

The majority of equipment is finished (including magical equipment).

Enemies are fully functional and working. They have AIs which can be customized, they are slightly randomized when spawned. They give exp, drop items and so on.
There isn't a large variety of enemies at the moment, but that'll be worked on.
However, enemies that are included are relatively decent!
An example is a low level medium boss (level 20 basically). It is a vampire, strong, moves fast, hard to hit and a ton of Hp (5000, when the average monster that level has 400-700).
It has a normal attack (200-300 damage, a pure tank at this level would have between 2500-3000 Hp), a bite attack (400-600 damage), can shoot shadowy bolts of energy at you from a range (probably change this to bats, but damage is 300-500), it can summon vampire bats (weak pests) and drain blood (200-400 damage, which is used to heal it's self, when this is used however the vampire enters a blood lust, which makes it attack harder and faster (does 100 more damage or 200 when bite it used and it's attack speed goes from 1.1s to 0.7s) and use drain blood more often, unless this effect is dispelled it will become more or less constant, making the fight a lot harder).
For this fight at least 3 people are needed, a tank, healer and someone to debuff the blood lust effect. Damage dealers are optional but will make the fight easier and quicker.

There is 2 dungeons, but I am working on another 2.
There is a low level cave (1-5), inhabited by rats, bats and slime. This cave is short, and has no notable features really, it is more of a passageway to a future dungeon than anything else.
It's boss is the zombie of the ex-town hobo, who one night got drunk and wandered in the cave, only to be mauled (or gooed) to death by slimes.

There is a medium low level cave too (15-20). It is a sealed cave, situated behind the church. Inhabited by a lot of undead creatures. Again, it is a cave and has few notable features to it.
It includes 3 bosses.
A defiled corpse come back to life for vengence.
An ancient skeleton tasked with guarding the cave from intruders.
And an ancient, sealed vampire (hence the reason the church was built near the cave, so the vampire could not escape).

I am also working on a twisted magicians tower. A level 25-30 dungeon with magical beats and monsters, it'll include lots of nasty traps and twisted puzzles.
And I am working on the generic inn basement, filled with rats. It is a very low level dungeon, more like an introductory dungeon than anything, full of rats.

I am also working on basc NPC features. At the moment there is basically... Talking (and it is very simplistic and not finished yet). I will be adding a few simple quests, shops and a bank to store stuff.

Anyway, once all this is finished (maybe 2-3 days, a week at max, depending on how bad work is!) and the game is polished up a little bit, do you think it would be worth releasing as a small demo (if only to test things out)?