First investment, navigating Delhi's hidden costs

Did a site visit to D S properties in Karkardooma last week. Builder quoted a decent ₹1.6 Cr for a 2BHK. My first property investment hai yaar, so I'm honestly nervous about hidden charges. Matlab, stamp duty, registration ke alawa aur kya extra costs lagte hain? Are there charges that only pop up at possession? Also, pre-launch pricing ka kya scene hai? Is it really cheaper than buying later, ya just a marketing gimmick? I'm leaning towards a construction-linked payment plan. What's your experience, especially with D S properties in Delhi?