Census

[nzoomed]

Big envelope over there, unopened, waiting for the 7th. It's cheating to open it early isn't it?

Your allowed to open it anytime.
The odd thing is last census, they were very lax about when you had to fill it in. Once before the rules were you could only fill them in on the night of the census, not the day before or after.
Now they are telling us that we can sign them any time, well thats how i remember it last time. I did mine online and entered the code, the fact that it allowed me to do it online any time, seems to indicate they dont mind any more, or else it would have prevented you from doing it until that day.

got ours last week in the middle of the rain, was completely saturated, so i'll be filling ours in online

The envelope only contains the code needed to access it online, there are no paper forms in the envelope itself.