The length of a repayment holiday is largely up to your lender. Most lenders will take into account your individual circumstances, and set up a repayment holiday that meets your needs.
Be aware, however, that while your repayments are reduced or paused, interest is still accruing on the principal of your home loan. This means you’ll eventually need to either increase your repayments or the length of your loan term in order to make up the difference.