The way that you know that the berries are ripe is to look at the bush. If the robins are busily eating all the berries, they're ripe.
FWIW, we also planted strawberries in a 4x4 raised bed. They never produced much, so we yanked them out and planted flowers and fennel (don't do that) and whatnot. However we missed a few runners, and the strawberries spread, escaping the baleful shade of the coneflowers and forming a perimeter about the central garden, that actually produces strawberries. We usually get a few (mice get more), which is fine for a no-maintenance/no-expectation plant.
It took about 25 years for the grapevine to start producing significant quantities, and by then all the kids were grown, but grandkids learned how to harvest them anyway. We squeeze a lot of plants in a tiny city lot. You can't feed a crowd off them, but that wasn't the point.
