HOW LONG SHOULD IT BE BEFORE PUPS COME? SEEMED TO PUSH EARLIER 2O MINS AGO AS IF FOR POO BUT NO MORE SETTLED IN HER BED NOW.NO PANTING OR SIGNS OF DISTRESS.

All breeds are different. So tell us what your breed is and then someone with that breed may be able to give some advice.
The heading is waters broken. Each pup has a sack which contains pup and placenta. With each pup born you will get greenish fluid. If you have got this and nothing else then keep any eye out as sometimes if a pup is too large to come or breech it will be the fluid and nothing else. So keep an eye out.
If all that is happening is a clear or pinkish mucus coming away then that means the plug is loosing and she will have pups.
If she pushed 20 mins ago then she will push again soon. Sometimes it is a gap of 30 mins then another push. All breeds are different. Some will hardly push and produce a pup within minutes others will push for an hour and then a pup will come.
Always if in doubt ring your vet on call tonight to let them know your bitch is in pup tonight and you may need some help. Or ask their opionon.
Get your flashlight out and take her on the grass in your garden for a small walk. This can sometimes move things along. But take a towel with you and good flash light, just in case she thinks she wants a poo and pushes a pup out. Someone else hold the flashlight if possible.
Remember to keep her calm, warm and quiet in between times. She wont need an audience of people watching as this can put them off pushing. Also if they dont particular like the bed area to have pups they will put it off. Sometimes they think they would rather have them up the corner, or on the sofa or what ever.
Take care and hope all works out well.
Nutkin