I am building an 8x10 cottage/shed in my backyard. I have very little prior construction experience. I've been planning well but executing poorly, so nothing is perfectly square.  

I am at the exterior door trim phase. The door jamb and the sheathing are flush/plumb in the top left corner (i.e., creating a flat surface to nail trim pieces). But they are way out of plumb at the top right corner. And, the *extent* to which these pieces are *not* flush gradually changes from top to bottom on both sides of the door (and along the header).

The closeups show the issue better. The first photo makes it look like the top left side isn't flush either, but that's just the glare from the flashing tape dipping in the gap where the shims go. 

Grayne PVC shingle siding (similar to vinyl) has been delivered. The shed corners are trimmed with 1x6 wood trim pieces, so I was planning to trim the door in 1x4 trim pieces and then run J-channel around that. Now I am concerned that the wood trim will turn out looking rather crooked.

**Questions**:

 - Would using a moulded trim piece [like this][1] (photo attached)
   solve this problem?  
 - If not, should I just try to notch plain 1x4 trim pieces before
   nailing?  
 - Is there perhaps a putty compound I could apply to fill in/flatten
   this space?
 - Is there some other established solution for this problem?

There is not much space between the soffit and the top of the door, so I would even consider trimming the door entirely in J-channel (or equivalent), if there is a way to make it look right.

Any suggestions/insights are appreciated. Thank you for reading. 

[![The Door][2]][2]
 


[![Top Left Corner - note my hand is flat against both surfaces][3]][3]


[![Top Right Corner - notice the difference in position of my index and middle fingers][4]][4]


[![Header][5]][5]


[![enter image description here][6]][6]


  [1]: https://www.homedepot.com/p/Alexandria-Moulding-WM-444-11-16-in-x-3-1-2-in-x-96-in-Primed-Pine-Finger-Jointed-Casing-0W444-93096C/205902090?g_store=&source=shoppingads&locale=en-US&&mtc=Shopping-VF-F_D30-G-D30-030_020_MOULDINGS-NA-NA-NA-SMART-NA-NA-New_Engen%20PL3&cm_mmc=Shopping-VF-F_D30-G-D30-030_020_MOULDINGS-NA-NA-NA-SMART-NA-NA-New_Engen%20PL3-71700000085463734-58700007262103169-92700065179582283&gclid=Cj0KCQiA2ZCOBhDiARIsAMRfv9L3ORK0gDDmvanyVVuBwnY53953oCJrVt8SjOpO2wyrICUnAlhtvoUaAo4_EALw_wcB&gclsrc=aw.ds
  [2]: https://i.sstatic.net/Ta0pd.jpg
  [3]: https://i.sstatic.net/LtmlB.jpg
  [4]: https://i.sstatic.net/rAiFT.jpg
  [5]: https://i.sstatic.net/Ha3un.jpg
  [6]: https://i.sstatic.net/OiJ7s.png