Why do you want Son so much?
I look at coming up fixtures for transfers and definitely for my WC last week. You don't want to be looking 1 or 2 weeks down the road and thinking "shit, I need to make tfrs, the fixtures are awful".
https://www.footballfallout.com/fantasy-football-planner
You've probably seen this/something similar.. lets you choose how many weeks ahead you want to see. Over the next four weeks, the easiest (on paper) fixture lists are Leicester, Wolves, Arse, Liverpool. I've got 8 of their players.
City have a blank coming (and Chelski). Are you going to hold them through the blank.. AND risk rotation?
Everton and Villa fixtures tough too (you've got Watkins/Richardson).
WC it.