Lilmama1011, I wouldn't (@ the bold). Your moisture should come from DCing. I believe if you use anything that isn't a heat protectant and then flat iron, you will burn that product and create that horrible smell. Also that product will make the protectant not adhere well to your hair and thus put you at risk of exposing it to damage from the heat. I believe this will also make your hair revert if exposed to humidity since the "moisturizer" got in the way of the protectant working well.
I never use anything but heat protectants on my hair when I flat iron and my results last all week ie until wash day and my hair reverts fully as soon as I shampoo.
I suggest you follow
WestNDNBeauty's method.