I have seen a lot of people receive their bags only one day later even between Tokyo/Kyoto! I think two days is what they generally promise but as long as you ship in the morning, I think there's a good chance it'll arrive next day. I use air tags when moving bags even at WDW. I will probably ship my carry on as well depending on how my packing goes. I will have to do a trial run at home of how much room my stuff take up and if I can fit everything into a backpack for two days just in case. The tricky thing is I have to be a bit strategic about laundry so I need to make sure I have my bag back on a certain day...gotta plan out all of the moves ahead of time so I can just check my notes each day of what I need to do!
I am an overpacker though, so my suitcases always end up so heavy. Japan is going to require a lot of sacrifices as I am usually a 2-3 outfits per day type of person. Packing only a few outfits for a two week trip is NOT my usual method. But I'm a shopper too, so I know I need to leave room to go crazy at Uniqlo and GU for clothes alone (and Disney, obviously)