Buying Off Plan with 1-4-1

We are considering buying properties off plan and using 1-4-1 receipts to part fund this. Whilst I would think that the principle is fine it's partly being considered in order to help us get money out of the door and meet spend deadlines. If construction doesn't start within say a year, would that be a problem ?
  • We're doing something similar - but having taken advice, we concluded that we couldn't claim use of 1-4-1 upfront, and so agreed stage payments with the developer - 10% deposit, 20% at breaking ground, 20% at golden brick, and so forth.