Three business class seats is a difficult one with the exception of Beijing and Shanghai.
I would suggest that you check
https://travelhacks.azurewebsites.net/.
I've just ordered three business class seats myself - a long weekend for myself, my husband and his brother. We experienced that three business class seats to US regularly opened up about four months in advance. At the moment, there is quite a lot 7 to 14 days availability to Washington DC and Chicago the coming months - up till the start of march.
I am pretty new to this, so thanks for the link, never used that site before. Nothing available for Easter, though... We travel husband, wife and son and have to go during school holidays, which must be a reason for the problem.