Now, everyone might already do this but I have noticed occasions where posts are apologising for being late with regular events like linky parties. You can avoid this by pre-scheduling your post ahead of time so that it will turn up at exactly the time you wanted.
When you are writing a post you will see the Post Settings sidebar at the right. If you click on Schedule 2 options will come up. Automatic and Set Date and Time. If you click the button Set Date and Time you will be given a calendar to click for the date you want - and to change the time just click in that box and scroll to what you want - or type it in. Don't forget to click done when you are finished.
And then you still have to click the big orange button at the top which will say Publish or Schedule! Thanks to Kristina who pointed this out - easy to miss the last but most crucial step!