i agree with doing it on sunday.. and small is nice..
do you have other children around her age in your family or friends? we did a big one for shane at our home in CT.. and it was nice..but he had noo clue how many people were there.. so it didnt really make a difference to him. but if you do want a lot of people for you(because i understand how special it is).. maybe the park would be a nice idea??
my brother did a play/gym place.. where they invited family/friends with other kids..not too many adults… and they played there for a couple hours. i am not sure if you have a “my gym” or something of that sort in NY, but it was fun.