Is there a way in Excel to deliver first instance of a number in a list of errors logical and number values?

Question

Here is the reverse 2 way lookup formula that delivers column headers by matching first instance of numbers beneath and getting colnum to index function.This formula works fine if there are no duplicate values

Sample data

Pr/Mo	jan	feb	march	apr
pro1	2	3	1	4
Pro2	5	6	7	9
Pro3	10	9	11	12

Formula: $A$6 value is 9

=Index($B$1:$E$1),,Sum(if($B$2:$E$4=$A$6,(Column($B$1:$E$1)-Column($B$1))+1)

If function returns : {False,False,False,False,False,False,False,3,False,1,False,False}

3 is recquired here which is first instance not 1 but how to using formula not VBA.