Timing of NIC payments

[Curious Beast]

I'm so used to having client's pay the 'magic amount' each month to give them an NIC history without incurring NIC I have realised I don't know the exact rules...

Is it necessary to make 12 payments to maintain an NIC record, or is 1 enough? A client has worked for a month as an employee and paid Class 1, and is now set up as a company. They don't want to set up for PAYE until next year, is their single NIC payment in 13/14 enough for the whole tax year, or is there more to it? Basically have they already ticked the box to say 'NIC contributed' for the year and don't need to do it again?

I realise there is a tax saving to be had by paying the magic amount, but that aside are further payments needed this tax year?

Many thanks!