No worries. Fall/winter spinach grows slowly, but it'll usually wait around and kick in high hear during warm winter spells or when end of winter begins. You'll be ahead of the game then. Covering it with row cover or the like will get it to grow a bit faster/bigger during winter, too but unless you already have some it wouldn't be worth the extra expense.
Shoe (lookin' at poke chops for supper tonight, but not with spinach nor cinnamon!)