Starting GH now is a fine idea. I would start with 2iu though and add .5iu every week as long as side effects don't bother you. Some people get sides like CT, some don't. You may want to come off right before your show, about a wk out, depending on how much fluid you're holding...some of that will depend on how much you are using.
For gearon your prep, I'd start with long acting test and an anabolic like EQ, then in the second half, switch to your hardeners, prop, tren and add halo in the last 3-4 wks. Dont forget your AI to help control estrogen, dry out and look harder