We started getting party invitations once my oldest was mobile (@7-8 mos) for 1st birthday parties. It was awesome and we did it in turn. It allowed us to make friends and get to know the families who our babies were spending their days with. Don't feel odd about it. People will decide to come or not. It will be their decision.
If you do go through with the party, remember to have a treat for the babies who are not ready to eat cake yet but know about food
