Not my first 1911, but first Officer's size (I think that would apply to this pistol).Is this your first 1911?
The 1911 takes some getting used to, especially the trigger. But once you do it will probably be the most accurate 45 you own. The short barrel of the 1911UC also takes some getting used to; very unforgiving of any kind of flinch (we all flinch now & then).
Concentrate on your trigger pull. You want to pull the trigger straight back, which usually means you need to be able to feel the left side of the trigger face (for a right hander).
I'm sure your groups will shrink to a fraction of what you're seeing with your first outing.
The SIG 1911UC is a fine handgun. You're going to love it! The two of you just need to get better acquainted.