I have a very simple answer: when your ear no longer holds back your brain you’ve done enough ear training.  If you can hear any melody or chord in your head and find it with your fingers 100% of the time (even if it takes a moment) you are in a good place as a composer.

If you are struggling with the finding of desired pitches narrow it down by asking yourself if the unidentified pitch is higher or lower than your current audition pitch. 

If you’ve tried the higher than/lower than method and haven’t succeeded, try singing it to yourself and finding it that way. 

If you fingers can transcribe everything your brain hears – congrats! – you’ve qualified for the big game.  Now you just need to spend the rest of your life continuously expanding your palette  – and that takes a different type of training (I’ve covered some of the basic concepts in this youtube video).  

If you are improvise/perform ala jazz you might wish to  continue your ear training to reduce the time it takes your finger to identify the note.