You can add a gap or delay in your script by adding (gap: Xs) in brackets and mentioning the number of seconds you want the voiceover to be delayed.
From the edit script section:
As shown in the screenshot, you can manually add (gap) between chapters from the edit script section.
You can remove the gap from the video via the Magic box:
Remove all (gap) from the video.
Or if you have a pause with the duration mentioned, you can use this command:
Remove (gap: 3s) from all chapters.
You can add a gap between lines/chapters if you want only the media with the music to be playing.
You can add new lines between sentences as shown here.
Note: You have the option to change the speed of the voiceover now as shown here.