Override times for lessons - no default value

[Th3Ph4nt0m]

General Troubleshooting

• [x] I have checked for similar issues.
• [x] I have updated to the latest version.
• [x] I have checked the branches or the maintainers' PRs for upcoming fixes.

Describe the bug

The timeOfDay seems to be only the name, it is not really set as a value in the time selection. The time selection should take the default times as default values, so that the user can also change only the end time (the start time remains default).