The easiest time to apply Vastu is before you pay the booking amount.
For a plot, review facing, shape, slope, roads and surroundings. For a flat, study the 2D plan: entrance, kitchen, toilets and master bedroom. North-east toilets or a kitchen in the wrong zone are harder to live with than a paint change.
Share the brochure plan and a compass reading. A short remote consultation is enough to decide whether to proceed, negotiate, or look at another unit.
Buying right is simpler than correcting later.