OK, first to answer your question, I think having an overall plan is very smart, but I don't think you need to plan your every ride or anything. I would do as LuvBunnies says and figure out where to start the day. Other than that, I'd just say to make sure to plan out things that are priorities. For instance, if Fantasmic! is running and you want to do it, you may need to plan for it (especially if it's only running on "weekends", which would include Friday). In short, I find that if I don't make an active plan to see something, it often doesn't actually get seen.
If you want to see Peter Pan's Flight without waiting 20 minutes or more, then you will want to do it first thing on one day. If you have a Magic Morning with your ticket, then do it first thing on your Magic Morning. If not, or if you want to see it more than once, do it first thing on a non-Magic Morning day (which I believe would be Monday, Wednesday, or Friday). Dumbo is another thing you need to do ASAP, and doing the Matterhorn early is a good idea. The rest of Fantasyland should be much more flexible.
Without SOME sort of plan it's easy to miss out on some things you want to do. So I'd personally plan out the first couple hours of each day (even if it's just a simple plan, like, on Friday we'll do Peter Pan's Flight, Dumbo (if you want), and the rest of Fantasyland. I'd also plan which days you were figuring to do which shows--at least, I find it easy to miss daytime shows if we don't plan to see them, and if you do nighttime shows, much of your evening revolves around them.
And for unsolicited advice, if I were you, I'd consider trying the other thrill rides in
Disneyland. Since I hate drops, I find Splash Mountain to be the scariest ride in Disneyland! I can't say what you WILL want to do, but I find Space Mountain no more intense than BTMRR (though if you think the dark will bother you you might stay away). If motion simulators don't bother you, Indy will probably be appealing--my friend was terrified of coasters but she enjoyed Indy. The Matterhorn is really bumpy but otherwise tame. (Gadget's Go-Coaster is a kiddie coaster but tame.)
(Others may disagree but I think California Screamin' is terrifying, Mulholland Madness is a touch scary, and Tower of Terror, I wouldn't even touch, since I hate drops.

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