It is almost impossible to pick a summer squash too soon. Every fall just before a big frost I pick everything including those that are only an inch or two long -- and they are delicious. However, the ideal time to pick is when they are about 5 to 6 inches long. They will be tender and you will not have to peel or deseed them. If they get a foot or more long, they are still good to eat, but you might have to scoop out the seeds and peel them before cooking. Good luck. Gardening is so fun and healthy. Keep up the good work.