If I lose a bunch of weight or get tons of new clothes, that's when I go through what I have and donate.

just when i get in the mood

as needed...no real time as of year

I am also in the camp that keeps a bag ready at all times and tosses stuff in when it gets too full. It always seems so much more obvious what clothes I'm not ever going to wear while I'm tearing through them in the morning, or folding them after laundry day.

Unfortunately I have been lazy and I have 2 huge garbage bags ready to go! Maybe that should be my to-do for today

during the summer, but it should be more often. I have way too much stuff.

I do that on a pretty regular basis.

Whenever I thoroughly clean my closet out, a few times a year. Also a few things here and there if I just realize I don't wear/like/fit it anymore.

Only before I move or need to make room. I usually just wear my clothes until they get too ripped or something else that makes then unwearable.