Packing depends on when you can get to a washing machine. If you have access to one then I pack for a week ot two.
For a one year old maybe three weeks as sometimes you can go through a couple outfits a day.
Clothes/shoes that can interchange are best so you can dress up or down depending on where you go and cuts down unwanted/maybe items.
Roll your clothes instead of laying them flat as this takes up less room and helps with the wrinkles.

Leave a bit of room in your case for the gifts you want to bring back