Hi,
Welcome.
The FSI thermostat actually opens at 105°C, confusingly however the temperature gauge on the dash will show 90°C, this is normal. If it does not after 10 minutes of driving something is wrong. If it shows 90°C I would not be concerned the radiator is not getting hot, to some extent I have noticed the FSI engine self radiates when driving steadily without much need of the radiator coming into play. If you have a large red flashing thermometer on the dash stop driving immediately.
Please proof read your posts I found parts difficult to read.
Andy