Two kids, tiny flat: my upgrade dilemma in Ghaziabad

My 2BHK is bursting at the seams with two kids now, so we need a 3BHK in Ghaziabad for sure. We're eyeing Raj Nagar Extension or Vasundhara for good schools, but also checked out a Swaraj Homes project near Jalalabad. They had a pre-launch offer for a 3BHK at ₹75L. I'm honestly not sure if pre-launch pricing is actually a discount or just a way to lock in buyers early. Did anyone here buy pre-launch? Did you see real savings compared to open-market prices later? Also, regarding payment plans, my bank pre-approved a loan. Is a construction-linked plan always smarter, or is a larger down payment better if possession is still 2.5 years away? What's your experience with these payment structures?