Kohlrabi

They are usually ready to harvest in 3 to 4 months and grow to about the size of a smallish cabbage so I don't think it would work very well for you tbh. Most crops for winter/early spring harvest will do most of their growing over the period you mention of June to October and then just tick over over winter and with some another short growth spurt in Spring so not sure what to suggest as suitable for you, hopefully someone else will have a bright idea.