You could try riding 2 or 3 times a week to see how you and your family feel about it at first. You may find yourself not getting home much later than when you drove. I know for me, my bike commute was an incentive to not work late.

As a single parent I actually worked out my schedule that allowed for me to drive the kid to school, park in the student / visitor lot at the high school next to the elementary school, and bike 20 miles to work. It only took me 1:30 to ride vs. a 30 min drive most days, with a good amount of hills along route. After school she'd stay for the after school enrichment program (funded by my tax dollars so why not take advantage of it) then hang out with her cousins in town until I picked her up around 7:30. We still had about 6 hours a day of 'family time'. I'm sure it would've been harder to work out a different routine to squeeze in an hour or two of riding in the evenings without leaving her home alone.