There is nothing wrong with canvassing at any time on any day really, although I wouldn't knock any later than 8:00pm, or after dark in the winter months.
You will always find someone who isn't going to be happy whatever time or day you call. When this happens, just thank them for coming to the door and move on.
It helps also to keep in mind certain events/celebrations etc., as this may have a bearing on the type of responses you may get. eg I went out canvassing one FA gup final afternoon, and soon found that this was not a good idea!
The more you knock, though, the sooner you will achieve your goal.
Best wishes,
John