Like most trails, hours are usually dawn to dusk, which changes with the seasons. Though I am sure of you wanted to hike it at midnight you could as there are no gates, facilities, or personnel. Google does not have those options as most businesses do not rotate hours like a park or trail. There are no days that this trail is closed.
Google is wrong. You can hike earlier than 9 and later than 5
I've definitely hiked this earlier than 9. You park in a dirt lot that's right off Schoolhouse Rd and you walk about a half mile to the trailhead. I don't see how it could ever be closed. They may close a gate that doesn't allow you to drive up to the trailhead, but I've never accessed it that way anyways. Everyone I've seen walks from the dirt lot up the road to the trail. I personally would risk hiking this trail outside 9-5 and even on the days Google says it's actually closed.
Thanks! Your answer is awaiting moderation.