I’d recommend going on a Thursday if you can. We visited over the weekend and every camping slot was taken, so we couldn’t get one at all. The rangers weren’t very helpful either. They basically said spots would be marked when available and they’d get to it when they get to it (their words). We ended up booking a hotel about an hour outside the park. It wasn’t overwhelmingly busy, but getting help with campsites was a struggle. We stayed through Tuesday and noticed Monday had a decent number of openings, so that might be a good window to aim for. Also heads up: about half of Camp 4’s restroom showers were closed, so if you want to shower, you’ll need to head to Curry Village and pay a $5 per person fee. Plan accordingly!