No calendar, on purpose. Every construction stage falls due within 14 days of a notice from the developer that the stage is finished. The Rules set the percentages and the order; they set no interval between one notice and the next. A table that prints “6–9 months” beside these figures is showing a builder’s estimate in the same weight as the law.
Why the payment climbs. You are charged only on what has been disbursed, so the instalment steps up each time the bank pays another slice. The figures are the fully amortising payment on the amount drawn so far, over your whole tenure — how most Singapore banks present a BUC loan. Some packages are interest-only until TOP instead: cheaper during construction, identical afterwards. Ask which one you are being offered.
The stamp duty clock starts the day after the instrument is first executed (s 47), not on the day itself. The booking fee is set by each project’s agreement at “such amount as set out in item 2 of the Fourth Schedule”, not by law.