Ukraine doesn't have the know-how or logistics to maintain F-16s, hence the long waiting period. Any airfields in Ukraine with F-16s are likely to get struck and destroyed quickly by Russia.

It is a repeat of the Leopard, Challenger, Abrams tanks. The West postponed sending them as long as possible because they knew they'd get destroyed and wouldn't live up to the hype. But boy did the hype feel good.

I'm guessing they're negotiating for Poland to fix/maintain F-16s to then transport them back to Ukraine because no way will they actually take-off and land in Poland. They do the same with Leopard tanks and Caesar SPGs, they get shipped to the EU for repairs. I imagine Poland is being difficult about it because of the protests and the unpopularity of supporting Ukraine military among the Polish population, hence the delay.

All of these deals and arrangements happen behind closed doors.