It would be easier to do the cast on on a 16” circular needle, then switch after the set up rounds as it was hard to push the stitches around the 24” circular .
To refresh my memory on how to work the end of the rounds when switching colors, I reviewed this YouTube video : Two Color Brioche in the round
Now I remember how to lock in the MC at the end of the brk round / beginning of a brp round.
( Quite a helpful Video when you have not worked a two color brioche for a while).

I used the larger needle just for the bind off.

I love how this cowl came out.