having worked the census last time around. No authentic, official census worker will ask you any questions without showing you a Census ID with an expiration date of no more than sixty days from when you see it. They are required to advise you of the confidentiality of your responses and that no personal identifiable information will be disclosed or connected with you. Any information made public won;t be made public for 72 years. They have to tell you all of that before asking anything more than whether the address they think it is, is correct upon your agreement. They can only ask a set of questions and that's it.
So when would someone show up at your place?
In March, they will be verifying addresses and hand delivering the questionnaire if you don't have your own mailbox on the address property. 80% of my state was hand delivered so we had major ground operation. All others will come via USPS in your mailbox at the address. Read the heading carefully and all the questions first.
You should not be asked for your phone number in the first three operations that should go on until June. After that they may contact you to see if you know anything about a neighboring property, like if it's a vacation home or permanent residence. Rather benign.
But always check anyone's ID if they say they are from the census, they've all been fingerprinted. You can be nice but don't give them any more info than they ask for, which is on the questionnaire. And read the top if the form to make sure it's official.
ETA: read the BOTTOM of the form too!