I am in my 3rd week post op and shedding most of the tranplanted hairs. It look "uneven" on my hairlines because there is hair in spots and none in others.

Is it ok to "trim" the newly tranplanted hairs for a more even look? or will it impede the process of them shedding and growing back?

I don't think...I shaved my head after 3 weeks and new hair started to grow in the 4th week. Probably just coincidence but the point is that it didn't affect newgrowth at all. By 3 weeks the HT's are firmly in place. As long as you don't injure your transplanted area in any way (especially bleeding) you will br fine.
I'm almost 8 weeks now and everyday I see new hair popping up...I had 2100 grafts.