Every year there are a few southbound hikers on the PCT. A lot of them don’t finish the trail, and I’m not sure why. Maybe it’s because the trail in southern California is a real anticlimax after the beauty of the north. There is very little water and you don’t have the spring flowers that make hiking S.Ca. in spring interesting. Also the short days in November make it harder to get the miles in between the water sources.
As to difficulty - you will have snow the first few weeks. That can be a hard way to start a hike, especially since you are in wilderness. The four southbounders we met had had to do detours because of the snow in Washington.
If you can’t start until June, you might consider starting at Kennedy Meadows or Walker Pass and hiking north with or a little behind the crowd. Then flip in Sept/Oct when you reach Manning. You still risk the emotional let down of hiking S. Cal in the fall - but your start will be a little easier since you would be hiking with others and navigation wouldn’t be an issue.
Ginny