I have a puppy who's almost 5 months old also. Her momma and my other girl, Foxxy, who's 8 mths old are already trained and won't go in the house or will use the pp pads if they must go in the house(when it's raining snowing, etc.). It does make me feel bad to have her confined when the rest of us are running around so unfortunately, right now my house is pp pad central!! lol. I have a 3 story house and I have 2 pads in the living/family room, 1 in the dining room (same floor as living) 2 pads in the basement and 2 pads upstairs (1 in my room, the other in the hallway. That just about covers all basis. If you don't want to leave her confined while you're home, that may work for you too. I did it for both my older girls..they're trained primarily to go outside but pp pads are for just in case..
Good Luck