Just change the date at the bottom of the WRITE POST screen to a date in advance. Save all the new stuff as drafts and edit them as you need, and have the release date set for whenever you want them to appear.
I recommend that you set the release date when you have finished with your final edits as, depending upon your version of WordPress (I think it's fixed in the latest version), when you edit the post it might change the date when you click publish. Known problem but I think it's fixed.
And this way, since you are moving it from Draft to Publish with the date holding it back from the public until is appears, you will have better control over the release.
Also, if you are paying attention, the day may arrive and it won't be there. The TIME also plays an important role, so if you are looking at 9:30 in the AM and the release time is 9:45AM, it won't be there until after 9:45AM. I've freaked on that a few times.