Yes, Aquariel AB, post doesn't like the 'less than' symbol in the post, it chops everything off when it sees it! Your formula is correct but it is missing the date 2012 check.
Trying again, and if it doesn't post correctly this time I'm giving up!
So my formula post minus the 'less than' symbol, but replaced with the @ symbol is:
Assuming the Total Sales figure for a specific customers 2016 purchases is located at cell reference D4 and their first order date is located in cell B2, then the entering the following formula into cell K4 would produce the result desired:-
'=IF(OR(D4>=250,B4@DATE(2012,1,1)), "Y","N")'
(need to change the @ character for the 'less than' symbol i.e. the keyboard character that points opposite to the > symbol
If that works ok, you can then copy and paste the formula into the cells K5:K27, which presumably will be used for checking other customers records that follow the first customer record row at 4 i.e. rows 5 through to 27.