No. Most buyers purchase 3 to 60 months before they fly, and that is the point.
Phase 0 covers everything to gather before you leave your home country, which is far easier to do at home than from Italy. Buying early also means you land already knowing the 8-day Permesso di Soggiorno window exists, which is the deadline that catches most new arrivals.
The guarantee runs for 60 months, so it covers you well past your move date.