If you feel better about waiting til this weekend when it's cooler then go for it. (I'm in Salem, and in the same boat weather wise). But I'm pretty sure when your ready to take the bowls out, all you will need to do is show one of them where the water is. Bring one of their beaks close to the nipple, flick the nipple with your finger and let the water drip at the tip of the beak. You will only need to show one. The others will learn from her.
Also, are you using apple cider vinegar in their water? It's great for them! And mine seem to love it. In fact they won't drink plain water anymore. If you aren't, read up on it. There are a few discussions on here about it. Good luck!