However, in reality, it is neither the GoB nor BAL who is working directly on the project. It is Japanese companies under JICA. They do everything meticulously and not without a proper schedule. So, if the date has been given by the Japanese, they have taken into account all the related work activities and adverse factors before they have prepared the main schedule and there is every possibility that they will complete it.
However, so far, I have not read anything from the Japanese source about the schedule. It is always the GoB source. So, I am not very sure. Stations, exits, yards, railway double-track lines, signaling system, importing the carriages, trial runs, ticketing system, etc. and importantly substations and the electrification work along the entire route.
I can see too many work items that need quite a time to complete. It is not the nature of the Japanese people to set arbitrary dates to appease others. Anyway, it is OK if the actual date of completion takes a little more time. Japanese do not allow commissioning without doing a job 100%.