At least for Japan region JMB members, you will be able to request your post-flight JMB miles online. JAL will roll out that feature in mid Feb. But this is limited to international flights only for now.

For JAL Group international flights, you can request the post flight credits from 5 days after your flight until the 6-month deadline.
For JMB partner flights, you can request the post flight credits from 14 days after your flight till 6 months after.

For details, you can refer to JAL website: http://www.jal.co.jp/jalmile/use/int_flight_mile.html