There is a saying among RC enthusiasts. A nose heavy plane will fly and land, and fly and land. A tail heavy plane will fly just once. (Or something like that). Moral to that story is that you do NOT want a tail heavy plane. For a beginner, it's better to have something that is slightly nose heavy than even slightly tail heavy. Even most experienced pilots will not like tail heavy.

Do the math on the power to weight ratio and see if what you have is within those limits. If it is, then shift the position of the battery until it works in your favor (move it foward to shift the CG forward.. rearward to move it rearward..) then, as you suggested you were going to do, have someone with experience fly the plane. See how it performs. If it's ok, then fly it. If it is not, then make adjustments as necessary then have him/her fly it again.

Best of luck.

CGr.