With only a couple days left, spend as much time with your 4 year old as possible, it's the last time he will be an only child. I have a 3 year old and a 6 month old and know how hard it is to get organized. The first couple of months were a little chaotic, but I do have advice for after the birth of your second child (congratulations!)
I made a list of bigger organizing things that need to get done (filing, organizing closets, etc.) to do at 'some point' and when I have time I tackle one of them. I also used to worry about how to get organized, but remind myself that housework/organizing can wait, but your children growing up does not wait. I had a friend send this to me and I've put it on my refrigerator to remind myself of this...
Too Busy
The dishes are still in the sink.
Dirty laundry is piled high.
Somehow the entire day,
Seemed to just fly by.
I made a "to-do" list
I meant to follow through.
But there were other tasks,
That needed attention too.
Like cheering on my son,
As he took first steps into my arms,
Making sure he stayed safe,
From all potential harms.
Cuddling on the couch,
And reading a favorite story.
Helping him explore the world,
And marvel at all its glory.
So the chores will have to wait.
They aren't that important anyway.
Because I was simply too busy,
Loving my child today.
To keep the house 'almost' clean I have designated each day of the week for one chore...Monday laundry gets done (usually) Tuesday bathrooms get cleaned (sometimes)...etc. I leave one day of the week to get caught up on things that don't get done. This way when I see something that needs to get done, I don't worry about it because I have a day designated for just that purpose. I've learned not to get upset if things don't get done, however. If my child says 'mommy play with me', that is more important than getting other stuff done. Try not to worry about things so much just be there for your kids, everything else will fall into place. Good luck!