I and some others have tested this and have found it to work reliably.

When first starting an adventure, before sending any armies:

1) Go to adventure island
2) Read Quest
3) Return to Home Island
4) Send Armies
5) Wait a few minutes

When doing this, the armies will transfer in the correct amount of time.

In addition, when sending armies back to get more troops, wait until the camp is finished deconstructing before returning to home island. Sometimes this will result in the generals transferring instantly home.

We have yet to find a workaround for waves after the first, as they are still hit and miss. But this is better than nothing.