I recommend a grouping system for things like clothes & toys. We had a number system 1-5 (#1 was things that needed to be unpacked the 1st day, as the number got higher, you could wait longer to unpack). Since you are in Canada, I can assume you could put summer clothes in a higher numbered box. Since you will be staying with your parents, I would suggest dividing fave toys into things to take with you for the month and things for the #1 box. It guarantees an hour plus of free time when your DC get more of their fave toys back.
I am also a fan of labeling the boxes, we had a "go" box for each room (1 bathroom box with TP, toilet bruches, towels for the fam, & toiletries (a shower curtain, etc)). One for the kitchen (dish soap, dishwasher detergent, dish scrubber, a few hand towels, and enough dishes to get us fed sandwiches/cereal/etc the first day or two and cups). For each bedroom- bedding, clock, lamp, etc. that way on moving day, we had to get everything situated, cleaned up & dusted, and then unpack the one go box for each room. Every other box was gravy.
we also used the divide and conquer approach, I went to the house and made sure everything was clean (wiping down baseboards is fast in an empty room, then I would dust/vacuum the stuff from storage as it came in the house. My DS put shelf liner in the kitchen cabinets & pantry for my while I was doing the other stuff.