There are times you want to create a page, prepare it, but not make it visible to site visitors till the appropriate time comes. In my experience there are two ways to do such a thing after creating a page:
Simply go to Page Properties: Custom Attributes, select Exclude From Nav, Exclude From Page List, Exclude From Search Index attributes and check Yes. This will remove every link to your newly added page, so no clue at the front-end, this page already exists. This will do the job for most of the cases.
If you create an important page, want to nobody see it before the launch day you can play with the permissions. Go to Page Permission and uncheck Guest & Done.