I am here to help you Stef , I am actually doing what you are doing going one chapter at a time, but for me its not 3 chapter per week but rather 1 chapter per week but I can boost my speed to 3 chapters per week and just dont pay so much attention to detail as I currently do. My goal so far was to focus on Pharo 4 and not Pharo 5, so I can make a Pharo 4 release (github release and github tag) and then move to pharo 5 at least one month before pharo 5 is released.
But because I know that your MOOC is based on Pharo 5 maybe you want to move UPBE directly to pharo 5 (not hard to do because we have already documented some parts of pharo 5) which works for me too.