Frankly in this scenario I'd choose one of the two and skip the other unless the standby line is unusually short. We do 9 - 10 day trips so there are 2 days for each park with time left over. This Nov our grand kids will FP to Frozen so we'll be in this boat at lease once.
Bill From PA
Why skip? It's perfectly possible to ride both early, especially with the third theater at Soarin'
OP: Test Track, then Soarin'
Why skip? It's perfectly possible to ride both early, especially with the third theater at Soarin'
OP: Test Track, then Soarin'

If you cant (or don't want to) use single rider at Test Track start there and move to Soarin.
If you can use single rider at TT, start with Soarin.
We have FP for Frozen so want to hit both of these at rope drop. Which should we do first?? Thanks!