On one level, you know that it would be most correct to outfit your young son in the same type drawers, petticoat and dress that you put on your daughters. Realistically, few little boys (and dads) are willing to put up with dresses..
So what options do you have?
For toddlers, I do recommend a dress and drawers. Call them a tunic and pants if it makes you feel better, but a plain, untrimmed pair of drawers and a solid, light colored, untrimmed dress would look suitably correct and tolerably masculine. There is a reason that boys were dressed this way - it's practical for changing diapers, it is economic because you can use the clothing for subsequent children regardless of gender, and a loose dress and drawers is just comfy for running around in. White cotton was used for toddler and infant clothing because it could be boiled and bleached clean. As appalling as it is to think of your son rolling about in the dirt and grass in his white outift, it will bleach clean in a hot water wash.
Once your son is three or four years old, and realizes that he is wearing a dress, you can make a basic pair of pants and tunic or shirt.
Pants buttoned on the side, and had flat fronts - backs and fronts were identical. This enabled Mom to get double wear out of the pants, when the bottom wore out, the child simply wore them the other way around! Pant legs were untapered, and hems could be anywhere from just below the knee to above the ankle. Add buttonholes to the pants for a button suit (below).
If you are an experienced sewer, you can modify a contemporary pattern, or you can buy one of the reproduction patterns made by several companies.
For shirts, you have a few options. A "French Tunic" is a long sleeved, thigh length, full, A-line shirt that buttons diagonally from the neck to the hem. Period Impressions is one company that makes a pattern for this garment. Another option is to modify a modern, button down shirt. Miss Fannie and Miss Vera offer instructions for modifying a boys shirt here.To their words, I would add that you should buy a shirt in a larger size, so the sleeves have the appropriate dropped shoulder and fullness.
A third option is a "button suit".The suit includes a waist banded, skirted, front-button shirt and button-side, drop front pants. Buttons on the shirt's waist band are buttoned through button holes on the waist band of the pants. (These buttonholes will come in handy when your son is ready to wear braces (suspenders).
For footwear, scout consignment stores for black or brown leather (or faux leather) boot with a rounded or squared toe. No waffle soles, please!
Once your boy has reached the age of eight or so, he can dress in the miniature versions of civilian menswear. Many boys enjoy dressing up like soldiers, and while 19th century boys would have been equally eager to "play soldier" only the wealthiest of families would have been able to afford "mini-uniforms" specially made up for their children.
A final word on hair - boys' hair, if it is long enough to be parted, is parted on the side, not the center.
