I'll share my most recent experiences, with and without a GG reservation:
In May, on both of my Epcot days (5/1 and 5/5), I did not follow the crowd of rope drop people straight to Soarin'. One day I did Nemo first and one day I wandered slowly over there taking pictures, and ended up with a 10 minute wait one day and 15 the next.
In December (12/21), we had an 8:00am Garden Grill reservation and were finished eating at 8:40 (and had been visited by the characters twice, which was fun!), and as we were leaving to go line up for Joy and Sadness, guests were flooding inside after having been let into the park early. If we'd have gone right to the Soarin' line, we'd have been one of the first to ride.
It will vary depending on time of year, but I really think you should be fine and be able to ride Soarin' with a reasonable wait right after your breakfast.