Rajkot buyers: Down payment se negotiation ka funda?

Krishna Kunj keeps coming up every time I shortlist something for our 3BHK. Kids ke school aur safety sabse pehle hai. I heard from a friend that with builders like Maruti Group ya Ansal API, if you offer a higher upfront down payment, you can negotiate better on PLC ya parking charges. Is this tactic effective in Rajkot? Ya bas time waste hoga?