15 minutes is all you really need to put into it before you can say you did it and can log it.

Personally, I find I may give it that and then once I sleep on it I come up with more ideas.... you have all month to come back to it to add or change what you have. Remember, nothing is written in stone. Have fun with it. Who is this character you want to invest some time in?

You may also try interviewing your character and writing to find out what they think and want... just a thought.