K.A.
I had to pretty much live in a bra unless I was sleeping (I just can NOT sleep with a bra on). I put it on as soon as I woke up and took it off just before going to bed. I had to do the same thing for a few months after my daughter was born too. She was born in June so the sweat and the milk left things always moist.
The powder I used was Caldesene Baby Cornstarch Power with Zinc Oxide in the blue bottle http://www.caldesene.com/product#cornstarch
I would alternate with Triple Paste http://www.triplepaste.com/ Mine never became yeast infections but I got some nasty sweat rashes. I liked the Triple Paste more when it got itchy. A&D and a few others didn't work as well for me.