Spot discounts are real if you know when to push

Spot discount milna possible hai ya builder bas bluff kar rahe? Humari badi property bech ke Noida mein chhota flat dekh rahe hain, kids ab settled hain. Sector 157 mein Nimbus Realty ka ek project pasand aaya. Builder bolta hai no negotiation, but I'm thinking... spot discount ka koi secret timing hota hai kya? Matlab, month end ya quarter end pe zyada chances hote hain? Kya koi experience share kar sakta hai ki kab builders actually price drop karte hain? Aur kitna expect kar sakte hain?