As a chemical engineering major, my 4 year plan is highly structured based on a complicated web of prereqs and classes only offered a specific semester (fall or spring).  Take a look here at the curriculum.  There is one class missing (ENCH 300 is the class, not ENCH 225 which is only available in the spring semester) from the fall junior classes from the biotech/bioeng track, but it is otherwise the schedule that is recommended to graduate in 4 years.  The class that I would say is important to take freshman fall semester is ENES 101 as it is really built to be an introduction to engineering and gets you working on group projects.

Also, great choice of majors :)