I'd recommend a tunnel vision approach for you OP.
Pick the most important room (kitchen to make cooking easier? Lounge for peaceful evenings? Where stressed you out most?)
Pick a room and then pick the easiest task: the first pass for the bin. A quick sweep of anything you arent attached to that you can bin without thinking about. Envelopes, broken crockery, whatever.
Perhaps spend a day or two before making a mental list as you live in your space.
A second pass might be for things that don't belong in that room that you can temporarily move (without worrying about finding a proper home for them)
Then a third pass for selling, and do this as you go along rather than creating a pile. Fwiw, I got sick of selling really quickly and decided I valued the space more than the item so I sent it to charity.
Leave anything sentimental til last as it takes longest and is most emotionally challenging.
Then another pass because you inevitably need to review the um/ah items and make a decision.
As for doing it with your son around, could you prepare a fun task for him the night before? Like hiding 20 rubber ducks for him to find in the same room, or asking him to count something or help you find something?
I have three helpful rules:
- Can I replace this in 20 minutes for less than £20?
- If this was an insurance claim, would I use the money to replace this item?
- Do i want this or do I want the space?
Good luck. Don't be hard on yourself. Even being ruthless it is going to feel like you're whole life for a while and take up headspace so don't try doing this alongside e.g. trying to lose weight, establishing an exercise regime, starting a new job etc because it will be mentally draining and need to be your focus.