This is a little bit waste of time to do this.

First, your flight is 5 months ago, your chance of getting compensated is slim to none.

Secondly, depends on how much your flight is delayed, also have to factor in what kind of delays, weater, ATC, mechanical, etc. If it is only an hour or two you are not going to get much of compensation. If it is a longer delay, I can't see why they wouldn't compensate you on the spot of your flight.

Third, even if you get compensated, you are more likely getting a voucher that can only use for that same airline again instead of cash or a check. Unless you are going to fly that same airline sometime soon, it would just be a waste.

I don't quite understand why you wait for that long to ask for compensation ?