If you have decided that a New Zealand bankruptcy is the most realistic way to resolve your debt problem, and you start now, you are likely to be bankrupt in plenty of time before Christmas.
If you start now with an IRD negotiation, there is also a good chance that things could be sorted well before Christmas.
Either way, if the debt is sorted, you will be able to relax at Christmas time knowing that the IRD will not be chasing you, and that there is no risk of arrest if you travel home (you will need permission to leave if you are bankrupt but this is usually easy to obtain).
By starting now, or soon, you will avoid the delays that arise when people apply at the last minute just before things shut for Christmas.