You should be leaving the laying bin in with her all the time. She has to have the option of laying her eggs whenever she wants to. I usually cover the front of my females cage with a sheet when she is ready to lay and never remove the bin until I see that she is skinny and at her basking spot and ready to take food. That usually indicates that she is done but is no guarantee. It will take my female a week to dig her hole and fill it in after laying once she starts displaying the behaviour. She will dig a couple of test holes over the week. Bottom line is, its best to give her access to a laying bin at all times rather than taking her out and putting her in one.