I sometimes have to sit in the car with the engine running until the inside of the windscreen de-mists.
Normally only when the temp really drops overnight.
Even wiping the screen with de-mister pad doesn’t really help. It clears the screen a bit, but still not enough to drive safely.
I have worked out a procedure to minimise the time I am waiting & close all vents apart from the windscreen slot.
Diesel engines seem to suffer worst for this. My Wife’s old Ka would warm up so quick that it took no time at all for the screen to clear & her subsequent 308 (1.6 Petrol) was also pretty good in that regard (one of it’s few good points).
But my old Ibiza & the current one, take ages to get the windscreen clear as the warm air takes so long to come through.
I’ve just bought one of those car dehumidifier silica gel bags to try & stop the inside form misting up. Put it in overnight last night & no misting up at all this morning, so we’ll see how it goes.