Remember that you will need to purchase your ticket either a few days before the journey or on the actual day of travel. Therefore, you need to choose the most convenient booking office, from where you will also buy your ticket.
If you have not bought your ticket in advance, but have made an advance booking, you need to arrive at the station earlier, say an hour or two before the Expected Departure Time (EDT).
In terms of getting to the station where you intend to board from, it is advisable that you ensure that you get on the earliest bus that would deliver you to that station at least two hours before the indicated EDT. Our experience is that many passengers make mistakes by using public buses that depart late or delay along the way and end up reaching the boarding station too late and find the train has already left. This is the case for passengers connecting from Lusaka and the Copperbelt to New Kapiri-Mposhi. It is also the case in Dar es Salaam where road traffic congestions are rife.
You have no control over public transport; neither does TAZARA have that control. Therefore, play it safe. Look for the earliest and fastest means of transportation to get you to the boarding station.