All my females, except 2, are allready off food since a month or two. Some allready started refusing food about 4+ months ago as I lowered the temps in october, so it's hard to tell if you would go out from that
The females pictured in this topic allready had there glow, you can see it in the pictures as well, and had there last shed (before 'ovulation') 2 months ago or so.
But I heard from other breeders that there are females who didn't go through the 'normale shed-cycle' at all and surprised the breeders with cluctches which they didn't saw coming. And I even heard of females who continued feeding during the whole 'process' and started refusing just 2 weeks before laying eggs.

So looking at the sheds and going off feed helps in a certain way, but after all it ain't completely reliable....