Show off baby's first year with a photo display.
You could also use a plain photograph by using glue or modge podge to stick it to the square.
Once you have glued your photo to the sqaure you can glue your square to your board within the scored lines.
And you would do each month one by one.
I kept this very minimal but if you spaced out the boxes a little more you could add text between the rows “one month” “two months” “three months” etc. and engrave it to the board.