When to tell daycare about LO #2?

downtown80

DD is currently in an in home daycare.  State laws only allow 2 children under age 2.  There is another child there the same age as mine.  My husband and I are considering getting a nanny to watch both children once I return to work.

As some background, we have always said (to ourselves....not her) that we would probably be looking for new daycare as DD got a little older.  Our DCP is a great infant caregiver, but she isn't the best with the older kids in the manner that we would like. I'm personally not a fan of the food that she feeds them or the amount of TV that is watched, and I would prefer some more educational activities.  So the timing of #2 seems to work out perfectly with this plan.

Obviously, I will have to tell her that I am pregnant at some point.  But I am just not sure how to approach the topic that we might be leaving as well.  Do I just address that part later?  I am sure that she would understand, as she won't have room for another child under 2. 

Just curious of other opinions, and what others may have done in a similar position.  Thanks!