Index Match: First "1" after x

I'm convinced there's a super easy solution to the following

Basically, I'm trying to find the column location of the first "1" after the value stated in KP. (KR contains the correct results)

i.e. The first "1" after 287. (193)

The issue is that KP is variable, hence a conventional array doesn't work.

Also, the formula is to be replicated thousands of times - & solutions such as this:

Formula:

=IF($KT2=TRUE,IFERROR(AGGREGATE(14,6,$A$1:$KN$1/($A2:$KN2=1),COLUMNS(KU2:$KU2)),""),"")

.. crashes Excel!