Hi,
It's the ovulation that's the key - until you see that there is no gaurantee you are getting anything at all.
You can palpate to see if you can judge the size and number of the follicles (unfertilized ova ) - they start off small and get bigger and bigger as the process continues.
Sometimes at the end you can actually see swelling in the female because of this which is the "building" phase people talk about.
Of course sometimes the female decides not to lay for some reason and the follicles get re-absorbed.
But once the follicles are large enough then the female releases them to be fertilized - this is the ovulation and is a really really noticeable swelling.
Once she has ovulated something is coming out. If you managed to get a good count by palpating earlier you might even know how many somethings are coming out.
One of mine seems to have a build so large I have mistaken it for the ovulation twice in a row now.
How is she eating? The general wisdom seems to be that they will not lock after ovulation or eat after ovulation either. So if she has locked since the last shed then it probably wasn't the pre-lay shed I think.
dr del