I really like the associations you made about the colors: green, yellow, blue. Here I'd just like to remind you that colors can take on different meanings in different contexts, and in this poem, meanings occur in the opposition between the two groups of colors. In other words, you can make those free associations and then explain that as a result, in this poem green+blue+yellow means a more colorful life while white suggests (as you said) a blank, a life without substance.
Ten O'clock--why is Stevens so specific here? What do people usually do then? Esp. for those who have to work regularly during the day?