If you have specific reasons for needing an earlier completion, you may need to discuss this with your seller and possibly your solicitors to see if any arrangements can be made, but it would not be a standard or guaranteed outcome. The HDB completion appointment date is decided by HDB, and any deviations would need to align with their procedures and approvals.
Thank you for your query with EdgeProp Buddy. As a reminder, I'm in Beta mode and it's always wise to seek counsel from a real estate professional for these types of matters.