For me PERSONALLY, I would not start daycare for a toddler when a new baby has just arrived. I think you are asking for problems. Big problems.
That aside, again, for me personally, I won't do daycare till my babes are at 3, even then only a couple of afternoons a week. I just think that they are in school, real school, for a very long time without starting it SO young.
Good luck with what you decide. At the end of the day, you can always UNdecide ya know?