My daughter is just finishing preschool and she too has a pump. My first advice would be to call your pump company. My daughter has a Minimed and they sent a certified trainer to meet with the preschool staff and owners. The trainer is coming back in August to train the school staff and the kindergarten teacher. This takes some pressure off of you and doesn't give them any more than they need to know. I did not give my preschool a choice. I told them her blood has to be checked at certain times and there was no budging on it. As far as snacks i asked for a list ahead of time, and attempted to figure out the carbs for them. I also sent along a copy of the Calorie King book for them to keep. They found this helpful. I also made very simple cheat sheets for them like a list of Courtneys favorite foods and the carbs in it. This helped them not have to stop and look things up every time. I think meeting with them ahead of time and keeping it simple is the best. I also let them know that there was no 100% correct thing to do because every situation is different. We all, I am diabetic too, have days where we just run high for no reason or low and can't explain it. i made sure they knew I was only a phone call away incase there were questions. The owner of the daycare did tell me that she thought having the trainer come in was best for the whole staff. They felt better hearing a professional tell them that if they count carbs wrong its not the end of the world.
As far as checking blood, i told them to never hesitate even if Courtney says she feels fine. they are to do it at every and any snack, if they notice odd behavior or if she tells them she feels low. They always write it down for me too so i can see if she is having issues. Best advice though is to keep it simple. They don't need to know about filling the pump or programming it. i taught them the Bolus Wizard and that was it. Give them the basics, which is still alot of info, make cheat sheets and highlight most important spots, and try to relax. If they see you are relaxed about it I found it makes them more relaxed and comfortable doing things. Good Luck and please let me know how it goes.