Welcome to caching, and congratulations on your first find!
What martybartfast says.
If the hiding place is not an obvious one, then when you remove the cache put a marker, like a stone for example, in its place to ensure you replace it in the correct spot.
You've got an advantage, caching with children, as they can provide distractions, and as marty says people expect children to be doing silly things anyway.
I mostly cache on my own, and I've had a few situations where I've felt I was being watched by one or more individuals whilst I was signing the log and so on. If they don't move along, I have a drink, and a sandwich if I've got one, then make some imaginary mobile calls. If they still don't go, I put the cache in my bag and walk away, give it a while and then go back and replace it, assuming the people have gone, of course.
Do not go gentle into that good night.
Rage, rage against the dying of the light. (Dylan Thomas)