Advice for trip to HND on points

Super excited for our trip to Japan in May with my wife and two kids for our son’s graduation in May. When I booked the tickets to start I booked my wife and I in PS and then used global upgrade certificates to get to D1. That was a total of 527,000 miles for both of us, so pretty good deal. For our son I had to use full points to get him to D1 and it was 552,400 for him. Our daughter was a late add and was 284,700 for PS for her. My question for this group who has experience traveling to Japan, how far out before reasonable upgrade options exist for D1 to get our daughter upgraded? When I called this’d week it was 300K+ points each way and only got the leg from DTW to HND and HND to DTW. It did not include RSW to DTW and DTW to RSW. It was over $3k each way if paying cash. That seems crazy, so clearly not pulling the trigger right now. Any better ideas from this group? Still lot of seats available in D1, but also realize we are a ways out at this point. Appreciate any creative ideas from this group.