Therefore when Daniel 12:11 says to count 1,290 days from the "setting up" of the "disgusting thing that causes desolation" it must, be referring setting up of the United Nations in 1945
The counting does not start from 'setting up' as in creating/forming the UN, it starts from the 'putting in place' the UN.
The UN/KOTN is 'put in place' sometime during WW3 when it is given authority. At that point it becomes the 8th king. The UN could not be the 8th king upon it being started. It was a newborn in 1945.
[ 31 And arms will stand up, proceeding from him; and they will profane the sanctuary, the fortress, and remove the constant feature.“ And they will put in place (5414.) the disgusting thing (KOTN) that causes desolation.32 “And those who act wickedly against the covenant, he will lead into apostasy by means of smooth words. But the people who know their God will prevail and act effectively. 33 And those having insight among the people will impart understanding to the many. And they will be made to stumble by sword and by flame, by captivity and by plundering, for some days.]