I like your 3 tasks approach – very proactive!
Dont think there’s a ‘natural’ point to let people know, but it is important to choose the right moment. Don’t delay too long though, I felt a relief  when I started talking to my family and friends, and, of course, no one can help you with a situation they don’t know about, even if just by extending an ear or a shoulder or being on the other side of the phone in the evening.
Just going through separation now and even though we haven’t quite managed to separate physically yet, we certainly have mentally and emotionally and it already feels quite lonely outside work which keeps me going (sort of).
This forum is really helpful  with some great people always happy to lend an  at so you’re never completely alone…