I'm landing at Vienna airport on a Friday (work day) at 17h35 and I'm supposed to attend a meeting at 19h00 close to Stephansplatz in the 1st district. I have only carry-on luggage and a EU passport, flying in from a Schengen country, so I should be out shortly after 18h00.

What is the fastest public transport into the city center taking into account it is rush hour?

I'd like to be on-time to surprise my colleges at the meeting, who already started picking, like "don't worry we'll wait for you"