my grandad always said one pound of feed before xmas is worth 2 after, the point being that its easier to keep your sheep in condition than to regain condition prelambing, so bung the hay in early, it will come to no harm lying for weeks even on the park as they eat or not as they like, you can move it with the sheepies, i do with my gimmers and did when i just had a dozen sheep. i think if your asking the question then your instinct is to feed them so go on, enjoy it, i love feeding the greedy swine, its a grand feeling watching them tuck in