Your employer will determine the payments for SGC. Now if you are the employer then you can pay as and when you decide. Some only make a payment at the end of the year, but it also depends on how your drawings are being taken. E.G. some very small personal services company directors don't take any draw until June, when they know how the year has planned out. And thus make a single payment for SGC for the year.
Often in a good year one would consider making a forward payment for the following year, so under current rules your could dump $50k per person into Super. This sugar hit is a one off, as the following year you could not contribute to Super, unless you repeat the forward deal in the following June.
