You can claim the GST back when you lodge your Business Activity Statement (BAS). The exact period you claim it will depend on whether you account for GST on a cash or accruals basis. If your turnover is less than $2,000,000 and you are a small business entity, you may elect to lodge your BAS either monthly, quarterly, or annually.
If your turnover is more than $2,000,000 you must lodge monthly. If you lodge your GST annually, you’ll have to wait up to a year to claim your GST back.