Based on my experience of the Junkanoo festival, I would like to make following recommendations:
First of all, you should sleep as much as you can before go to the event. The parade spent the whole night from 2 am, and the transition time between different groups was kind of long. The long time would make you feel drowsy and tired. Otherwise, if you would not watch the whole parade, you may manage your time accordingly.
Secondly, bring some food to the venue. Having some food would definitely boost your energy and keep you warm, as it will be chilly in the early morning. However, I would not recommend drink too much beverages, because the restrooms were limited and unclean.
Lastly, feel free to communicate with staff and local Bahamians. They are really friendly and helpful. As they are more familiar with the festival, you may find more interesting things about the Junkanoo and the culture.