Wash sale question – buy before recognizing loss

Hey, I was wondering if the wash sale works for 30 days regardless if the stock was bought first?

I'm thinking of taking a loss this year on DIS but still owning long-term; I have a large long-term gain that was exercised and I'm hoping to offset it with DIS while keeping the holdings.

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I want to buy DIS and then sell 'loss harvesting' the same amount a day later.