Butternut squash - what to do with under ripe ones (etc)?

Hi again

Following on from my "Is this a butternut squash plant?!?" thread, I now have a couple of questions about my ACTUAL butternut squashes

As I mentioned in the other thread, I am going away on Friday for a week and wondering whether I need to harvest these before I go.

Also, from what my very inexperienced eyes tell me, some of them are under ripe. If that is indeed the case, is there anything I can do to help mature them? Are they still edible when eaten under ripe?

Here are a few pics. The last one is of the ripest one we have and I think that looks good to go. The others are less ripe and also quite small (around fist sized).

Many thanks

Max