Best route at the moment. (Toilet #1)

When you get into the game it's quite obvious where you should go.

You're in a blank room and there is a single door. 
Go straight down.

Once out the door speak to MJ(The Brown Man On The Right.)
Immediately go to the left afterward, straight downward after.
Enter the house and talk to the "Walking Butt" then go to the door on your left. 
Lay in the bed and wait for the screen to transfer.

Once that's done you've entered your first major area. The Area I call "The Mario Zone".
As soon as you exit the door on the left head to the right to the hallway downwards.
Once you're down that hallway go down the stairs on the left.
Mario has officially logged in cause now you're gonna be hunted and chased down by blood-hungry Mario's.
Go to the right until you get to a red box. Should be right to the table. Interact with it and then continue right.
Quickly up the stairs and then left. Keep going past the first door until Mario shows up.
Then turn around and go back to that first door. Go in it. Then Exit it as soon as you get in.
Continue left until you get to the door. Go in there then go to the large locker.
Enter the code "0 8 3 2".
Exit then go back to the stairs. Back down them and then to the door on the right.
Go inside then upwards to the fire. Interact with it and then turn around, and exit the area.
Head past the Mario painting. (DON'T INTERACT WITH IT)
You should see a Fire Extinguisher, quickly get it. 
Then head straight back to the door you just exited.
Interact with the fire and then head up. Make sure you speak with the Fire Extinguisher.
Head to the far right, enter the door and click the lever in the middle. 
Then go out the door and to the middle hallway. 
Ignore the door on the left and just keep going up. 
You'll enter a room with 4 Mario's, don't worry they are harmless. (for now)
Push the four Mario's onto the green and red panels.
Personally I think you should push the bottom left and then the bottom right. 
Then the top right then the top left.
There will be a single panel left. Interact with it and place the Fire Extinguisher there.
Go upwards after.
Just head right, and don't get scared when Luigi appears. He's Green and not a fighting machine.
Now, this is the tricky part when you get into the "Red Zone" head right then down.
At the first opening head right. Then go upwards.
Go right then down and there should be an "N" red mark. Enter it.
Grab the bathroom key and then skedaddle out of that room.
Head down and to the first opening on the left.
At the first corner head straight upwards.
There should be a "C" red mark. Enter it.
Head down that hallway and then straight down and continue down.
Head Left at the first wall. Then down at the red opening.
Don't admire the cow and keep going down.
Head left to the Mario painting but don't interact with it.
Let the cutscene do it's thing and follow the Fire Extinguisher left.
As soon as you get in that door head straight up.

You just got your first Toilet.
(More will come in #2)