The format for times is managed by preferences within Pimlical (so you can have different setings from the system settings). For a 24-hour clock, set the preference TwelveHourClock to False, and the preference: IncludePmIndicator to false.
By default, Pimlical uses one of its two own Time Pickers which is typically much faster and more efficient than the built-in Android Time Picker. However, if you prefer to use the standard, Android Time Picker, you can set the preference: UsePimlicalDateTimePicker to False, and Pimlical will then use the Android Date and Time Pickers.
Pimlical defaults to a time picker that displays the time in digital format with buttons to set a new time. The selected digit is highlighted in red, so if you tap the '1' button, the numeral 1 will appear in the highlighted selection and the higlight moves to the next button. You can tap any of the four digit positions to select the higlighted digit. There's also a :00 button that sets the minutes to 00, and an Am/Pm button to toggle between AM and PM (if a 12-hour clock is being used). If a 24-hour clock is being used (TwelveHourClock is set to false), then instead of the Am/Pm button, there is a :30 button that sets the minutes to the half-hour.
By default, when the last digit of the time is entered, that time is set and the dialog automatically closes. You can change that behavior if you wish by setting the preference: AltTimePickerAutoClose to False in which case, the dialog will not close until you tap the OK button. If you have the default setting, remember that you need to select the correct Am/Pm setting and timezone before you enter that last digit.
When entering a time, Pimlical will avoid an invalid time and make adjustments accordingly. For example, if the first digit is selected and you type a '3', that can not possibly go into the first position, so Pimlical sets the first digit to 0 and puts a three in as the second digit.
The Now button sets the current time and closes the dialog. The None button sets no time (for an event, that would set the event as having no explicit time, or what is considered in some calendar applications as an "all-day" event.
Other Time Picker
By default, Pimlical now uses the "alternate" time picker. You can also set the original Pimlical Time Picker, by setting the preference: UseAlternateTimePicker to false. Pimlical then displays a time picker which has separate buttons for each hour of the day and separate buttons for all five minute intervals. Some users of the earlier "DateBk" calendar application prefer this display. To set a number of minutes not on a five-minute interval, you would tap the button that corresponds to the start of the five minute interval and then tap the single minutes button in the row below (i.e. to set a time of 4:47, you would tap the '4' button in the hours section, the '45' button in the minutes section and then the '47' button in the single-minutes row of four buttons.
Pimlical defaults to displaying Home Timezone as the selected timezone, unless a date is being changed that already has an explicit timezone, in which case that timezone will be displayed instead. The Home Timzone is the one that is set in the preference: HomeTimeZone. In addition to setting an explicit timezone, you can also select AllTimeZones, which generates a time that is not affected by timezones (so if you set an event at 5am EST, it will still display at 5am in PST etc.).
For more information on Timezones, see the help file in this same section on timezones.