Entirely my fault as I mistook the date for my first day of employment when I arrived here from the UK. Is it just a formality to get it changed to the correct date (it's a few weeks earlier and I have evidence) when I visit the Kreisbüro for my next renewal or will my request be met with a stony face?

Speaking of renewals, this will be my fifth 12-month L permit in a row, so this time next year I will have been living here continuously for five years. Is a C permit just a formality?