Our Personalized Touring Plan software does not make recommendations regarding the time of day for which you should make FastPass+ selections.
Generally speaking, we recommend that you try to get FastPass+ times early in the day, closer to the original order that you see on an optimized touring plan.
The optimizer may move some of your attractions to the evening because of the lower standby waits then. In general, getting all of your FastPass+ selections before 1 or 2 PM is the best because you can actually get an additional FastPass+ after you use your first 3.
If you get your FastPasses in the morning or early afternoon you can enter them back into your plan and re-optimize and it will use those. If you can't get them in the morning, just go for whatever the earliest time you can get. The optimizer will sort it all out.