You could put a couch facing the window with a rectangle coffee table (with rounded edges). On one wall, add a wall unit (great for storage and a small tv) that has a shelf for a desk. To save money, you could purchase two unfinished bookcases, build your own shelf (make sure unit is secured to wall). For a more custom look, add finishing boards to the top of the bookcase and across the front of the desk and paint the whole unit. Add an area rug for baby's comfort. On other wall, a low module unit and place baskets inside to keep neat for toys and a mini bean bag or large floor cushion.

Start with a cozy rug for your little one.

I guess budget would play a big role. Not being a professional, I love resale store shopping because, if it doesn't work or you find something you like better next year, you can replace items without a financial hit. I would not buy soft furnishings used (never know what type of fluids might have soaked in) but you should be able to have some fun finding your desk, lamps and other hard furnishings leaving the majority of your budget for the comfy items.