addChild - onComplete?

Hello!
I’m making a program where you can design you own room (walls and floor).
My problem is that everytime I change the floor/wall, it disappears for about 1 sec (Because the picture I’m adding to the floor/wall is 2000x2000)
Here is the code:

mc.addChild(loader);
mc.removeChildAt(0);

I’m searching for a solution to make the *removeChildAt-*function to be executed just after the addChild-function is complete, so there will be no delay between the old and the new texture.
I’ve already tried ADDED_TO_STAGE with no luck.

Thanks in advance,
~Tompa