Females can start to lay around 6 months old, some will, some wont, some may never lay, but getting them to not lay can be hard. Some people on here have had females that havent laid until they were over a year old.
Find jannb's blog on laying bins, it can help, but for now, washed play sand taht is moist enough to dig in, but dry enough to dig thru, will work just fine,