For winter squashes there is the "thumbnail" test. Press your thumbnail directly into the skin of the squash. If your thumbnail pushes into the squash without much pressure, it is not ripe. If it pierces after moderate pressure, it is getting there. The skin should resist "firm" pressure. It takes some experience to know exactly what to feel for.

I'm guessing it is not ripe since it's only August and the leaves are all still plush and green. But your climate is different than mine. When I grow Butternut, I leave the squashes on the vine until all the leaves are dead, but before a frost hits. I aspire to leave the squash on the vine as long as it might possibly receive any nourishment from the mother plant. This is not like harvesting zucchinis. Even after harvesting like this I would prefer to store the squashes for a month or two. The are best quality about this time. If you have so many that you will be eating them over a long period, go ahead and eat some right away. But if you just have a few I'd wait until November. Or October if you just can't wait.

I've been having a pickle worm issue I think. Tiny little holes in two of my spaghetti squash with orange frass outside the opening. I guess I'm trying to balance leaving it on the vine as long as possible against getting and pests. If I pick them in another month, will they ripen in the house?

They will gain some sweetness stored in the house whether they are ripe or not. A vine ripened squash will end up superior in this respect. If not fully vine ripened, storage time potential will suffer, which may not be an issue. You may not need to keep them for 6 months.

Tyvm