I believe you can either program an end time only (car decides when to start charging to reach full charge by ending time) or start and end times (car will start charging at start time and stop when fully charged or at end time whichever occurs first). With start and end times programmed, the car will start charging immediately if plugged in after start time and before end time. I am reasonably certain the timers will not work if only start time is programmed.
If you want the car to start charging at 0030 every day and don't care about end time, then I suggest you program start time 0030 and end time before you would normally plug in so maybe 1700 or 1800 with timer enabled for all days.
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015; traded 8/10/2019 at 82,436 miles
White LEAF 2019 SL Plus purchased 8/10/2019