The single 6-month warning is hardly enough; I can't even remember getting it. I got a notification message on the day noise regs came into force across the EU, and immediately all my airline's B732s without hushkits were grounded. I was able to do the retrofits, but at the cost of significant disruption.
There is more notification of airport closures/moves, which (generally) have fewer implications for uninterrupted operation. Perhaps we could receive warnings at 12, 9 and 6 months before enactment, then monthly until the final date.