Hi there!
I am currently in the middle of my 2nd Primo cycle. I take 100mg every 7 days. The reason I dont split is because that's double the pokes
My first time with it I was cautious to see how I reacted, I started with 25mg /wk, then I went to 50mg, then cruised up to 100mg. Definitely needed to be on 100mg. I never got much out of my first cycle at the lower dosages. But that's me! I am 5'6 and 135 lbs, 34 years old and follow a strict diet, I am a figure competitor. Judging by your photos, you are in great shape and obviously know what its like to train and eat clean.
In my opinion, you could start at 50mg the first week and see how you do...then you can bump up to 100mg if all is well. If you start to experience sides, just know that its a whole week before you can go back down, thats the risk. But honestly, I never experienced any sides until I went up to 100mg a week and only after a few weeks of it. The first thing was my voice got deeper...noticeable only to family and close friends. Its not like I sound like a man. And I have some clitoral swelling, and some acne. But I find that if I am consistent with my face routine morning and night and take extra care of my face, shoulders and chest...the acne isn't an issue. I'm just used to having none normally.
I should also add that I am stacking 10mg of anavar along with this Primo cycle. However, the first time I cycled Primo, I took it alone and still got these sides. All of which went away after I went off.
Good luck!! Hope this helps!