Baby Registry? ungrateful?

Dominique
So I have a question, what is the best place to do a baby registry without it making me look high maintenance or greedy? My SO family are the ones throwing me a baby shower and I don't really have much of my own family who will attend, well his grandmother told me that it would be stupid of me to do one because their family won't bother to look at it, I tried to explain to her that I wanted one so that people know what theme of things I want for my baby and so they can see what I need and what I already have. I will be having some family and friends who do look at the registry coming to the shower. I just don't want his family to think I'm greedy or anything, but I do want people to know what I want for my baby. Am I being ungrateful? I mean I'll be happy either way just really what a registry and want people to use it!    
Also when is a good tim to start one? I'm only 20w3d and the shower won't be until march or April.