So I assume the census is Congressionally mandated to start 1 April 2020. That being the case, Trump needs to get those forms printed, sans the citizenship question.

1830-1880 and 1900 Censuses were as of June 1
1890 census not available apparently June 2 - I'm guessing June 1 was a Sunday (I just looked and it was a Sunday)
1910 census April 15
1920 census January
1930 and since that are available was April 1

The censuses were not all completed on those dates. It was just the date set for determining age and other date related info.

From my viewing of many censuses. It probably took about 30 days or so to complete them.

she had been told it could take as long as 10 weeks. it can depend on number of hires in the area, how easily accessible and responsive the people you are trying to count are, etc.

then there's a lot of work compiling the data, running statistics, reporting, and so on.

canvassing is only part of the whole census process.

I've reviewed over 2,500 censuses covering from 1850 to 1940. The majority of them were in rural areas. All censuses had date on each page and if stopped in the middle of the page the census taker would mark the new date. Back then based on my recollection of census taker name they would be assigned a complete township not including any villages or cities. I don't know if they did more than one census. But of course for cities it probably was different. I do recall some that were broken down by city precincts, wards or other districts.

The one thing I wish was known about each household was the person the census taker interviewed. It could be an adult member of the household, a child, a relative in the household, or a neighbor. The reason being that sometimes the info provided did not line up.

Last week, while looking up another relative, I saw the 1940 census for the house where I grew up, where at the time my great-grandfather was the owner and my grandparents (his son and daughter-in-law) and their kids also lived there.

My grandmother, who would have been 40, had her age listed as 35. I assume she was the one who lied about her age, not her husband or her father-in-law. Made me smile.