Configure day based on string input

```python
userinput = wednesday
usertime = "18:30"
schedule.every().userinput.at(usertime).do(function)
```

The above does not work as they do not detect the variable's value for `userinput` but works for `usertime`

Start by reproducing the example using a string variable for the day and the existing variable for the time, then inspect the scheduling API reached through schedule.every().userinput.at(usertime). Done means the day is selected from the variable's value and the example behaves consistently with the variable-based time input.

Written by the indexing model from the issue text.