First, you should keep up with all paperwork. Leaving it till the day before it’s due suggests a poorly-run business. Successful enterprises stay on top of their stuff and know where they’re going.
That’s why, when our new clients go on Xero, we suggest they have a coffee and code their GST weekly.
Some start-ups prefer monthly GST to receive early refunds. Some large businesses must do monthly GST as the IRD wants their money sooner than later.
Most businesses do GST every two months. This combines regularity with IRD payment manageability.
If you meet IRD criteria you can do six-monthly GST and invest the 15% to earn interest. But you must be disciplined so you don’t fall behind.
These are general comments. You should take independent advice before acting.