Anonymous participant - Since you are already here, I would only apply in Austria, which is far away, if you were planning to go there anyway. Wouldn’t make the trip just for the visa. If you are just leaving Thailand to apply for the visa, then use one on the embassies in the region.
Only upcoming holiday recognized by the Thai embassy in Vienna is on Oct 13, Oct 23 and Oct 27. Given that it is only September 23rd, not sure you have to worry about public holidays.