To fill in the newly added time slots you have two options: drag currently scheduled posts to any empty slot or regenerate your schedule and select the option to "fill in previously scheduled Posts."
Drag and Drop
If one of the newly created slots is for a time you'd prefer a post to go into, you can simply click and hold to drag and drop the post into the new timeslot. This is likely the best option if you only have a few posts to move, but if you have quite a few, you can check out the next option below!
If you're wanting to increase the overall number of slots per day, you can regenerate your current schedule, which will give you the option to automatically shift all previously scheduled to the newly created posts.
Head over to the 9-Grid and, near the top, click Edit Time Slots.
Next, in the weekly posting schedule page, click on the Generate New Smart Schedule button on the right-side.
Finally, select the box at the bottom to Shift previously scheduled Posts to fill in newly created Timeslots.
If you have any questions or get stuck, feel free to reach out to our team either by the messenger button in the lower-left of the dashboard or via email at firstname.lastname@example.org!