GT380J, mounting the spokes: 

The procedure of mounting spokes is well explained in an earlier GT750 post. Please read the post before continue on this one.

GT750 post:

http://mc.grenasberg.no/2018/10/28/front-wheel-spokes-mounting/

Front wheel:

As described in the GT750 post, always start with the spokes at the inner side of the hub. And don’t mix the spokes. Inner and outer are different. Get the details from the post mention above.

Turn the wheel and continue with spokes at the inner side of the hub.

Arrange the spokes before mounting the nipples.

Both inner sides done.

Next step: mount the spokes at the outer side of the hub:

Turn the wheel and and mount the remaining spokes

Done, all spokes are mounted.

Rear wheel:

Do the rear hub in the same way as shown for the front hub.

The adjustment procedure will be the same as shown in the GT750 post:

Adjustments:

http://mc.grenasberg.no/2018/11/04/spokes-adjustments/