I’m asking if the in-principle approval is the initial step, and then 14 days later the buyer pays stamp duty, but at this phase the buyer hasn’t even exercised the Option to Purchase—do you get what I mean?

Yes. For HDB Residential Resale Flats, the Option to Purchase must be stamped within 14 days from the date of HDB’s in-principle approval. It does not depend on whether the option has already been exercised or not.