Have had our cat for 3 weeks and she has been kept inside all that time to get her used to being here.
She was patrolling by the front door today so I thought she wanted out (I was advised that she would let me know when she wanted to go outside as she had always been an outside cat) so I opened the door and out she went...
She hasn't come back 
it's only been two and a half hours and I guess she is exploring our neighbourhood but the kids are sad and I kind of wish I hadn't done it.
A friend said she will come back when she's hungry so perhaps rattle dry food/treats and have tried that but no luck..
Just looking for reassurance she'll be back as she is very much wanted here (I have nightmares of someone 'adopting' her and us never seeing her again). I guess it's always this way the first time you let them out but am a cat novice and this is making me sad!