re taking the gun to a gunsmith for cleaning, it's about the same thing as taking the car to the mechanic when it's out of gas. Sure, the mechanic can put gasoline in your car for you -- but why?
As for the rest:
1.shoot at the door while they are kicking it
Bad, bad idea. Morally, it's bad because you don't
know what's on the other side of the door.
Legally, it's a bad idea because if you use a gun for self-defense,
you must be able to articulate how your life was in danger at the moment you pull the trigger. The door between you and the intruders pretty well means that your life isn't
yet in immediate danger, so shooting them is a very bad move if you want to stay out of prison.
2.wait till they kick it in and enter then shoot them
3.wait till they get in and hold them at gun point until police arrives
Those are both possibilities; which one you will use depends on a lot of different variables.
Some things to consider: does your state require you to retreat as far as possible even in your own home? (Some do, some don't.)
Are you able to get out of sight of the front door, or will you be in their sights the second the door comes open?
When the door does open, can you see whether they are armed? In some states, the mere fact that they broke in allows the homeowner to presume that they are armed and are there to commit a violent felony, allowing self-defense. In other states, that's not true; the homeowner has to see a specific threat (a weapon & some intent to
use the weapon) before he may use deadly force to defend himself. In still other states, there's a difference between daylight & the hours of darkness as far as what the homeowner is presumed to know. And in at least one state the homeowner may shoot to protect property, not just to defend human life, so none of the above applies.
If you can get out of sight from the front door, you might consider using command voice to make them STOP (or DON'T MOVE), but you need to know what you will do if they turn & run away instead. Shooting a man in the back is generally bad juju. If they do stop, you need to know what to do next; make them drop weapons, get their hands up (elbows locked, palms toward you), slowly turn away from you, move away from the weapons, get down on their knees and then flat on their stomachs with their hands out to the sides, palms up, ankles crossed, faces away from you so they cannot see what you are doing. Do
not approach them; don't try to handcuff anyone; and don't shoot anyone who isn't an immediate threat to your life. Then you can call the police, keeping your gun aimed at the bad guys, and describe the situation to them. Give the police a good description of yourself, make sure they know you are armed and the good guy, and then hope like crazy that the police don't shoot you when they arrive because you're the guy holding the gun. If you think that sounds like a lot of work with a lot of possible places for things to go wrong, you are correct. But if the alternative is shooting someone, you might want to try it anyway.
There are other reasons to hold your fire if you can. On a sheerly physical level, you really don't
want a lake of blood soaking through your living room carpet if you can avoid it -- it's messy, smelly, medically dangerous, and hard to clean up.
If you do decide to shoot, you need to use good tactics.
Get out of sight from the door if you can, preferably off to one side. There really isn't anything in a standard living room that will stop a bullet, but if you've got something that will, get behind that.
Consider crouching low and aiming upwards into the center of the attacker's body, so that if you miss the bullet will be less likely to strike an innocent person behind the person you shot. Or hide high and shoot aiming downwards -- not just so that your bullet will strike the ground rather than a passer-by if you miss, but also because human beings rarely look upward when they are hunting and your attackers are unlikely to see you first if you are higher than they are.
If two people enter and you believe you need to shoot, aim for the bigger threat first -- if one has a gun and the other a knife, shoot the gun holder first unless the knife holder is closer to you and has seen you.
***
Actually, though, with all that said. You did not ask about the simplest and most likely effective tactic -- shouting through the door. "GO AWAY!! I HAVE CALLED THE POLICE!! GO AWAY!!" Seems to me, from the description, that the intruders positively did not want to tangle with an
occupied dwelling. So let them know you're there and if they run off, that's a win.
pax
That crap is for movies. You don't know who is on the other side.
) 
