My procedure is such that when a female has her pre egg-laying shed, I will put in an egg laying box with her 5 days after that date. Generally, she will lay within 48 hours of my giving her that box, if she is satisfied with it.
Remember that the girl is carrying an entire next generation in her, so it would behoove (sp?) her to get them safe and sound in a hurry. Any predator that catches up with her, also wipes out that next generation.
What I have found is that once a female sheds her skin, she is immediately looking for the perfect place to lay her eggs. I suspect a female would lay even sooner if I put in an egg laying box immediately after the shed, but haven't experimented much with it. But with the way I am doing it now, most will lay 5 to 7 days after that shed.
A lot of people mention the magic 10 day number for egg laying. My belief is that is the point where the female is not longer critical of the place she lays her eggs. She has been searching for that perfect place, but all the time the eggs are growing and she gets more frantic to lay them. When 10 days have elapsed, then it's an 'any port in a storm' situation for her now.
The longer it takes for a female to lay her eggs, the more likely that she is going to have problems. The eggs are growing, she is getting weaker from frantic searching, and a situation is shaping up for egg binding.
Simply put: The sooner you give a female a perfect place to lay her eggs, the sooner she will lay them and the better off she will be.
Of course the question is going to be, "What is the perfect place?"
Most people make the mistake of not putting enough egg laying medium within the egg laying box. They leave a gap between the medium and the top of the box. We use Tupperware style plastic containers with a 2 to 3 inch hole cut into the top. Peat moss is used for the medium and is *packed* into the container. By 'packed' I mean pressed in tightly. The female will forcibly push her way into this container, and make herself a nice little burrow where she will feel safe and secure, and it will seem to be an excellent place for her to lay her eggs. Remember that a LOT of predators would just love to find a clutch of snake eggs to eat, so she is concerned about not only finding a place conducive to their getting the proper moisture and warmth to hatch, but they must also be SECURE against being easily found by predators.
Hope that helps a bit with the strategy of providing a female what she needs to lay her eggs and feel good about her job.