Not in the sense that it used to be possible to book them a year in advance. It's now the normal 60 days. I don't know the -exact- timing when seats are released and it is possible it is slightly different to JAL's own awards, but not substantially.
On the other hand, whereas you need to book JAL domestic awards five days in advance if you're using JMB, you don't if you're using BA. You can even just go to the airport and book the next flight out while there on routes that have plenty of flights.