We advocate making the lay bin a permanent part of her viv to eliminate all the guess work of when to put her in the bin. Some people put the bin in the viv when they think it’s time but again they are trying to time it and you also have to greatly disturb her viv to fit it in there. Having the lay bin as a permanent feature of her viv also, and probably most importantly, eliminates very stressful handling at a very sensitive time. And I’d you don’t time it correctly the first time you will have to stress her out repeatedly until you get it right. Moving her to the bin also proves to her that she is not blending into her environment and is completely exposed. She will not lay if she feels exposed, she requires privacy.
To sum it all up, yes you can move her to the bin when you “think” it’s time but trying to time it has numerous downsides for your Cham, all of which can be life threatening.
Having her bin in her viv 24/7 is the way to go.