That's a tough one... maidening a plane is tough if you've never done it before. It's best if you at least have someone else there to adjust the trims for you while you try to keep it in the air.

I've had very experienced guys maiden & trim out pretty much every plane I've built so far, especially the SPADs. I've retrimmed a couple of my planes after some major modifications since then, and it can get pretty rough trying to keep control and adjust your trims yourself. It can be done, but it may be an unecessary risk to your plane.