no, for my fist year of actually freestyle skiing i used non-twins, i learned 360, tons of grabs, rails and other stuff, just dont do any big tricks that u land switch with them! the 180 here and there is fine to, just remember to lean forward and revert quickly!
dont get twintips before skiing park, use what u got for now, get ok athen if u want to continue get twins for next year.
i hate it when kids buy twins before ever entering the park b/c they think its an absoulte must. for a beginner u dont need them, especially mid-season!