Question about criminal record

I just recently signed up for the CAF a few days ago and I'm doing the PSCA form right now.

The thing is I'm 36 years old(been a dream of mine to join and finally pulling the trigger) and the only time I've been convicted of a crime was over 15 years ago for a few grams of pot possession. All I remember was a $50 fine is what I received. I don't recall the date or year. Would I be able to mention that part in the "details' section or should I try and find the exact date before sending the file thru