S.H.
T....what a beautiful sentiment and friend you are. She may not know it yet, but you are a good friend to her. I'm sure she won't feel "intruded" upon and would welcome your heartfelt sentiments and gifts from the heart. As you write to her, I believe the words will come to your mind. Just put yourself in her place and think of what you would like to be told or read. Pray to know, if you are unsure. God will give you the light and inspiration you need.
One thing I enjoyed doing the first year of my son's life was tracking his footprints. I got washable black ink (a stamp pad I got at Michael's/Hobby Lobby), and each month, I placed his foot on it and then "stamped" a sheet of card stock with his prints. I marked the month on the paper, too, to keep track. It's so neat to look back and see how those little feet grew so quickly that first year.
Maybe you could do something similar for her, like a scrapbook, where she would just have to fill in a picture or two of the baby each month. Use your talents to bless her life; so, if you are good at something else, find a way to brighten her life with your talent. :)
I wish you all the best and pray she will know that your gifts are truly from your heart! How could she not? :) Take care!