So...it's 7:00 a.m. EST and time to book, what is the strategy? Do you go to the day where your LLMP tier 1s are hardest to get first? For example Slinky Dog? Or go to the LLSP that are most important to you? I realize that you have a better chance of getting early times the later in your trip (we have 7 park days) but I would prefer to use the LLMP early in the trip and use the second day at parks to relax and smell the roses. I understand that LLMP are more important in Epcot and HS - so should I book those first? I am probably overthinking this, but I don't want to end up kicking myself later. We will be in the world March 7-14 so busy, but not busiest? I liked hitting the parks and running for the Fast Pass. It felt like everything was possible!
I want to start off by saying the strategy you choose is always somewhat going to end up a matter of personal choice and luck.
I'm also assuming you are staying onsite.
1. One bit of strategy I use is to look at the pricing for all the parks each day of my visit. The lower the price, the less crowded Disney thinks that park will be that day. On days when the price is lower, I've tended to get better LL's.
2. With LLMP compared to prior versions of FP, often the first prebook options WDW spits out are about as good as you are going to be offered. Others may have a different opinion, but if you just roll with the prebook options WDW gives you and pay with the cc that is on file with WDW, then the whole process only takes about 5 minutes.
3. If Slinky is a priority, then it is a good place to start, and book it for the 2nd half of your week.
4. You get to see what your pass options are before you pay for them, so if you don't like the available options, you can decide against buying LLMP for that day. (and change your plans to buy it for a different day instead?)
For the best LLMP prebook options, book LLMP for later in your trip. If you plan to buy 4 days of LLMP, odds are high that you will get the best options for days 4-7, with very so-so options if you try to book LLMP for day 1.
LLMP works best in MK.