The LC was out of town the weekend Leonel was born, so my attending nurse helped me BF him about an hour after he was born. I remember her rubbing my nipple to get it to harden and trying a couple different positions I think (gosh it's all such a blur already!), but ultimately gave me a shield to use because he hadn't latched(flat nipples). Sure enough it worked. Didn't think twice about it until a day later a different nurse saw me using it and said to make sure I weaned him off it ASAP because it can cause supply issues...at which point I panicked and read up on their use and couldn't find a darn positive thing about them.
Our ped said his wife used one for 4 months when his son ripped it off her and decided he was done with it, and when I did finally get to see the LC she said she would have waited longer to try without the shield but it's okay (he'd gained weight fine at the checks we had done). She said to just slip it off, try to get him to latch without it, etc.
Well today he ended up latching and eating a whole meal without the shield! But this is rare. Very rare. Usually he'll lick around, nuzzle it, maybe close down on it but then look angry (!) and get upset and push away until that shield goes on. I don't want him to get too frustrated too often at the breast.
So, how often should I be attempting to get him to latch without it? I had wanted to wait until we had gotten the hang of BF in general before teaching him something new, although I do my best to make sure his latch is decent on the shield ("fish lips") so the position of his mouth shouldn't be something new for him to learn.