I would make 3 FP+ for the earliest possible, adjacent times, so they'll all be used up/expired before noon -- 9am Mission:Space (just to use it up), 10am Frozen, 11am Spaceship Earth or Character Spot (again, just to use it up).
I'd hit Test Track at rope drop, then Mission:Space, then Frozen at 10am, then another attraction or two of choice, arriving at SSE/CS at 10:55am (there's a 5-minute grace period before your FP+ window where you can use it ahead of time - might as well use is ASAP), then immediately try to get a 4th FP+ for Soarin'. Most days, you should still be able to get a Soarin' FP+ if you try before noon. In fact, I would imagine that getting a 4th FP+ for any of the Tier 1 attractions is only going to get easier once there's another one (Frozen) for people to choose.
If you preferred to start with Soarin' and then try for a 4th FP+ at Test Track, just substitute one for the other in the plan above, and then substitute something closer to Soarin' (like Living with the Land) as your 9am "use it up" FP+. You could also then do your SSE/CS/whatever/second "use it up" FP+ at 10am and save Frozen for 11am, so there's less running around.
More (pre-Frozen, of course) info. here:
http://blog.touringplans.com/2015/05/06/fastpass-plus-availability/