All Nippon Airways Mileage Club - How to check what type of plane you get: really?

good morning, I'm new to ANA. I"m flying from LAX to NRT on 3/3. According to the schedule as well as the seats I paid for, I"m going to be on a 777-300 with the new biz seats. I"m a veteran UA flyer and their schedules and planes shift from minute to minute. Is there a website (ala UNITEDCARGO.COM) that one can check to verify exactly what plane I will be on? And if so, how many days out are you able to look at? I chose ANA over UA's crappy 777's out of LAX just for the possibility of trying out the new seats. Also, I know that there are NO guarantees as to availability. I just want to be able to monitor and check it.
thanks in advance for your replies

On long haul routes NH very, very rarely substitutes aircraft, and generally gives at least few days notice if they do. I've never experienced a sudden change without warning. You can verify what plane you will be on by checking the seat map.

On long haul routes NH very, very rarely substitutes aircraft, and generally gives at least few days notice if they do. I've never experienced a sudden change without warning. You can verify what plane you will be on by checking the seat map.

UA/AC should employ that strategy. thank you