Crumb72 said:

When do you know when it's time to pick the butternut squash??

Any time after the rind has turned tan should be ok for immediate use.

For storage, the rind should be tough enough that you can't pierce it with
a fingernail, and the stem should be as hard as wood.

For best flavor, leave the fruit on the vine as long as possible without
risking frost damage -- this may mean covering the fruit when light frosts
are possible.

--
Pat in Plymouth MI

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)