I have a daughter that turned 5 today and a son that is 7. My advice is that you need to talk with your wife about what her expectations are. If she is good with you riding everyday and her taking the child to/from daycare, then ride on. You do need to re-asses this situation in a few months to see if it is still working out for her and be willing to change your commuting pattern if necessary to keep everyone sane.

You don't mention how much more time you spend commuting via bike vs car. That is usually the biggest family issue.