We've taken our daughter at 3 months, 14 months, and 22 months. I don't think she has any memories but we LOVED each trip and each trip we enjoyed seeing the smiles on her face and reactions. (Even at 3 months, she had reactions to what she was seeing.) Plus, vacation is special time when we are all together, not working, and just having fun.
I've been told "Oh, she won't remember it...why don't you wait until she's older??"
1) We will remember
2) We love going to WDW, so why would we stop going to for 5+ years.
3) The photos are priceless.
4) I do all kinds of things for my daughter that she "won't remember" that costs money such as Disney on Ice, zoo membership, etc. Are we just supposed to stay in the house until she's 4 and can have good memories of things??