Here are some ideas from Mary Abella, Home Stager with A Little Bit of Red Interior:
1. Put laundry baskets in all the rooms where toys accumulate. When you get notice of a showing, go into each of those rooms, fill up the basket, and put the basket in the car. After all the baskets are in the car and the house is ready, either drive off or go for a walk. Buyers are looking at your house, not your car.
2. Place high chairs, bouncy seats, and other baby furnishings in a neat line-up in the garage for showings.
3. If there is a bedskirt under a child's bed or crib, scooting toys, clothes, school papers, and all other kid's stuff under the bed works. Nobody checks under the bed. They DO check closets, so don't shove things in there.
4. Keep a couple of rags and spray cleaner handy for daily mishaps. Treat them right away, before they dry up and are harder to remove. WD40 takes care of crayon "art" on walls and cupboards.
5. Don't forget all the playthings outside. Corral them into a box in the garage for showings.
6. Straighten up/clean house every night after the kids are in bed. Then, when you get them up, make the beds first thing, get them dressed, then feed them. That way, if you get a call for an immediate showing, you won't have to refuse it.