I found the maybe baby pretty useless, it never showed ferning for me even though opk's and cd21 blood tests confirmed I was ovulating. I was following the instructions to the letter and still got nothing. I borrowed it off my friend because she wasn't using it, it didn't work for her either.

I'd stick with the opk's - you can get them cheap from Lullaby Conceptions in packs of 20 etc.