Hi Tammy, I usually wait till the warmer weather comes too. If you think its warm enough I cant see it hurting, but if it gets chilly later I'd suggest putting a thin rug on just so he/she doesn;t get a chill.
Does he/she live out all the time or is he stabled at night?
I bathe my horse before a show or comp or if going to pony club and he's really dirty! I don't think it gets as cold here in winter :) so i bathe him all year round but i always have some warm rugs/towels ready in winter