depends when you are going, but keep in mind RSR fastpasses can run out anywhere from 2 to 4 hrs after opening. TSMM gets to about a 45 min wait very quickly in the morning, sometimes falls to 30 min, and has no FP option, so I agree with the advice to try to get that done first. Soarin line is not so bad sometimes and usually can get a fastpass with a not too long return time, and shouldn't run out of FP until very late. I would worry about soarin the least.
option 1)
Since Soarin is not far off the path to TSMM from the entrance, 1 person grabs soarin passes as everyone else goes to TSMM first thing, return time should be within an hour (or do they start return times later?), runner joins the rest in line at TSMM, 30-45 minutes has passed since opening.
Grab RSR FP right after TSMM as soon as your return time starts for soarin (eligible for 2nd FP), RSR should have an early afternoon return time at latest. Go to soarin to use FP, or else ride soarin before getting RSR FP if your eligibility will not come up for a while.
option 2)
Grab RSR FP on the way to TSMM, head back and do soarin while you wait for RSR return time, or wait to grab a soarin FP after you are eligible again if you are against riding it without a FP.
But honestly if you are at rope drop and go straight to RSR, then TSMM, then soarin with no FP for any of them, you'd probably be able to do them all within 2 hrs. That's not too bad, but waits can do weird things, RSR can go down, so options might have to change.