hi lisa,
you need to give it time. and you need to not stress out about it - i know you want to, but it will hinder your recovery, especially since you're going back to work so soon. (which btw, any chance you could wrangle 9 more weeks instead of 5? if you're US, they have to give it to you if you ask)
but back to your original question, i think i started cluster feeding around 3-4 weeks, right after that first growth spurt. i had more success with that than with a dream feed, but there are many posts about successful dream feeds too.
sounds like your routine is going well so far!