Hi Calvin ( and Dan) ,

lock off ( complete) your picture edit as soon as possible.

At this point bring the sound designer and composer together for a 'spotting' session.

In this session watch the film together and in addition to all diegetic sound in already in the edit , outline the areas where you imagine there to be :
1. music
2. sound design ( dialogues / effects / atmospheres)
3. a combination of the music and sound design

The sound designer and composer then take away a low res version of the edit with burnt in time code and then work on their respective areas.

When complete, all elements of the sound track are brought together for the MIX.

The director in collaboration with the film mixer ( and sound designer and composer) then decides on the relative level of the different elements of the sound track.

I hope this helps,

A