When using the browser to post content, you can now schedule when you want your posts to be published. It all takes place in the Post Settings area.
The first step is to check the Schedule post option. Notice that the Save and Publish button becomes Save and Schedule Post and the Schedule date section appears so you can set the day and time you want this post published. The "fine print" just under the date box will help you format the appropriate date and time.
Note that when you choose to make a post private, the Schedule post option is no longer available.