I've just begun capsule wardrobe. So I am learning to buy slightly before or at the start of a season.

But I'm still rather random. If it's something I really want, or know that I'll love for many seasons, I buy it right than and there. Other items I buy as I find them. The capsule wardrobe has helped me to plan my shopping and spending, and to be more intentional about my purchases. But I still enjoy a good shopping sesh.