What I’m about to say seems incredibly common-sense, but I have seen people make the same mistake time and again. The first day that you think you might be moving, go into your bathroom and look at your shampoos/conditioners/body lotions, etc. Do you have multiple bottles going? Are there some you could finish off before you move? Then go into your kitchen and do the same thing. How many half-eaten boxes of cereal, pasta, etc do you have? Anywhere you have supplies, go look! I see people looking shell-shocked by it all, because their mindset is that since those rooms are packed last, they don’t need to be dealt with until the day before the move. By then, of course, it’s too late. They have to either throw out usable stuff or pack/move/unpack it. They also have to dispose of things at a time when the recycling bin and the garbage can are probably at capacity.
So think about it early and save yourself time, effort and money!