Babysitter

My older daughter is in preschool and her teachers would like me to come in to help her use the bathroom before lunch. My 17-month-old has been coming with me, but I just feel as though it is so much in and out of the car time- doing drop off, coming home, going to the school to help, coming home, going to the school to pick up, coming home. I would just rather leave quickly run to the school, help my daughter and then come home and have my 17-month-old stay home. Usually around that time shes finishing lunch and just playing until I would get home and put her down for a nap.