welcome to the hobby!
quick suggestion: i would call up GLH and ask if you can swap out the magnums for something else.
magnums aren't very good for flavor or aroma, their main (almost exclusive) use is bittering. bittering with homegrown hops is problematic as you have no idea what their AA% will be. in my experience, the AA% on homegrown hops is lower - sometimes a lot lower - than commercial hops. so unless you're willing to brew a few test batches to figure out their relative strength (and ideally do side-by-side comparison batches with commercial hops of known AA%), using magnums risky - unless you're OK with a beer's bitterness being unknowable.
pesonally, i always use commercial for bittering and homegrown for late additions.