始発 and 終電: the first service, the last train, and the starting station
Distinguish the first-service and origin-station meanings of 始発 from the last train, keeping station and direction attached to timetable information.
The first service of the day
始発, read しはつ, can refer to the day's first service. 朝の始発に乗って、空港へ向かいました。 says that the first morning service was taken toward the airport.
始発の時刻を確認してください。 asks someone to check the first service's time. The actual time requires a timetable for the specified line, station, and direction.
The last train of the day
終電, read しゅうでん, means the last train of the day. 終電を逃したので、駅の近くに泊まりました。 says that the last train was missed, so the person stayed near the station.
終電に間に合うように、早めに店を出ました。 says that the person left the shop a little early in order to catch the last train. Read the purpose together with the action performed.
When 始発 identifies a starting station
この駅始発の電車に乗りました。 says that a train originating at this station was taken. It does not by itself identify the earliest train of the day.
First and last services at the same station may differ by direction. 上りの終電を調べました。 says that the last train in the inbound direction was checked; it does not cover the other direction.
Is この駅始発の電車 necessarily the first train of the day?
Show the answer and why
No. Here it means a train originating at this station. Check the time and other information to establish whether it is the first service.