If you count the Celtic oppida as urban centres, then yes, you can push it back a couple of hundred years before the Caesars. And there's some evidence of large-scale political organisations in places like Gaul and Britain in the immediate pre-Roman period. But the other bits of the package - notably literacy - are still missing. And by "Central Europe" I was thinking of the areas East of the Rhine and North of the middle Danube - so present day central & east Germany, Poland, Czechia, Slovakia, northern Austria & Hungary, - rather than Gaul.There were urban centers in Gaul, England, southern Germany and Pannonia by around 200 BCE and you early urban centers around 700 BCE in these regions far from Greek settlements as well.
In that sense it wasnt that slower than Italy or Iberia.
I hadn't heard of any pre-Celtic urban centres anywhere North of the Alps - do you have details?