I can add little to the above, except that ALWAYS do the vertical test. As posted above, do not lose and engine.
I did not see what engines you have with those three blade props. Unless the engines are .60's, I would suggest the first flight with two blade props for more efficiency. Make the take off run as long as possible, so that you have maximum air flow over the control surfaces at lift off. Plan on making the plane take off. Most do not automatically take off, but must be made to rotate.
This plane has very heavy wing loading, so make sure your use the rudders for turns and expect to use the elevator to tighten the turns.
Good Luck,
Twinman