Crochet Template For The Beginning of a One Piece Dress/Sweater/Jumper

One of the very first things you may ask when using this information is how many chain st's do I begin with?
If you think about making a hat and that you have to increase to a certain amount of st's for the hat to fit, that count will be the guide for you to make this to fit over the head of your subject
My subject is for a new born to 3 months and they need a hat with approx 60 st's that will fit their head, so I made a beginning ch of 60, then divided them as equally as I could to make a rectangle.
The rectangle is the beginning shape to fit the shoulder and neck area, that triangle will then become a square as st's are added to shape the garment and once again equally. 
Here is a drawing of what we are looking to achieve.

We also need to make these calculations knowing what yarn ply and hook size we are using.

This is my stitch count as I made the garment

As you can see, it begins in the shape of a rectangle

This fits well on my model

The increases are being made and the rectangle is slowly becoming a square

Which still fits well on my model

The square is now more obvious

The shape folds and forms a perfect garment

More rows and increases are made

Now you can really see the shape of the square, I have been using 10 ply and a 4 mm hook

If you would like written instructions, please leave a comment and I will be pleased to provide them.