You feel more comfortable if you have prepared some activities or task for your children the first day. I submit a link to learn a pile of animals with the initials. This is an activity for the digital blackboard so, you must connect it before the class. After playing with the animals and the initials you could promote a drawing about the children favourite animals. You might prepare a drawing and children colour it. That could be funny!
And here is the some images to colour it. In some of them you must delete the name in Spanish.