Usually in the week, it is not too busy.The weekend is a different story.So depending on which days you are going to be there,I would say a couple of weeks ahead should be fine.
I'll be coming up on a Tuesday and leaving on a Sunday. I can easily reserve a month or two in advance so it sounds like there should not be a problem.
Yes, we reserve for weekends pretty far in advance, but understand that there is more availability through the weekdays. Beautiful place to camp!
They do have some public group sites available too along trail and shelters too that dont require reservations. Their cabins and graveled sites are usually available up to a week away.
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