On the flip side of this, I spent only three years in undergrad. After graduating I did research full time for six months, but the research wasn't in my immediate field. I've been out for four years, now, with 3.5 of those spent teaching full time.
It's been clear that my deviations from the typical path have hurt me in applying to physics programs but helped with education programs. I think the "how long do I spend in undergrad" is a highly discipline specific question IF you intend to pursue graduate study. I strongly encourage you to seak out the advice of professors in both departments to see what they have to say.