3 ozs is a little under 100gms - the box of cream cheese is 200 gms, so just eyeball a half. I use the full 200 gms to make 12 oopsies at a time and it works great. I also add 35 gms whey protein to the yolk mix - makes it much more bready.
I also find them to be at their best on day 2 + - store in the fridge with a half open lid as they get a bit sticky if closed in.
Babs