One question that might be helpful in planning: what are your specific reasons for uncluttering before the move? I mean, I understand that having fewer things to move is generally helpful, but do you have any particular motivations?

For example, are you uncluttering because your new space is smaller than your current space? If so, can you roughly calculate how much stuff you need to get rid of in each area of your home, and use that as a guideline for your uncluttering?

Or, if you are trying to reduce your moving costs, you could figure out how much stuff you can afford to move, and then evaluate possessions based on how important they are to keep vs. how costly they will be to move.

Good luck with your uncluttering! Hopefully you have enough time that you can do it in lots of short sessions, and avoid too much knee pain.