Under-construction projects are a gamble, not an investment, right?

My kids' school admission is next year, and we need a bigger 3BHK place ASAP in Mohali. Budget hai around ₹1.5-2 Cr. We're stuck between two options: an under-construction project by Godrej near the Dwarka Expressway area, or a ready-to-move flat in Sector 80-90. UC mein price benefit milta hai but construction delays ka darr hai, especially with our growing family. RTM thoda expensive hai, but immediate possession aur no waiting. My wife ki priority safe neighbourhood aur kids ke liye good school access hai. Should we risk UC for potential appreciation ya RTM for peace of mind? Aap log kya suggest karte ho?